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Why it's used

Sulfamethoxazole/Trimethoprim is a prescription medicine that is used to treat certain infections such as urinary tract infections, middle ear infection (acute otitis media) in children, intestinal infection (shigellosis), serious lung infection in people with the weakened immune system (pneumocystis carinii pneumonia), infection of the digestive tract (traveler's diarrhea in adults). This medicine is also used to treat worsening conditions of the inflamed lining of bronchial tubes in the lungs. This medicine works by blocking the formation of tetrahydrofolic acid which is essential for the growth of bacteria. This medicine helps by preventing the growth of bacteria. Sulfamethoxazole/Trimethoprim is also used to prevent & treat infection caused by a parasite (toxoplasmosis) and lung infection caused by the fungus (Pneumocystis jiroveci pneumonitis).
When not to use
Sulfamethoxazole/Trimethoprim will not work to treat a viral infection (common cold).
Sulfonamide Antimicrobial
Co-Trimoxazole belongs to the Sulfonamide Antimicrobial class of medicines. Sulfonamide Antimicrobial.

How to use

Read the medicine guide provided by your pharmacist, your doctor, or the medicine company. If you have any questions related to Co-Trimoxazole, ask your doctor or pharmacist. Use Sulfamethoxazole/Trimethoprim as per the instructions provided by your doctor.
Co-Trimoxazole is used with food. Co-Trimoxazole should be taken with food to reduce the risk of stomach and intestinal (gastrointestinal) disturbances.
The typical dose of Co-Trimoxazole for adults is 800 mg of sulfamethoxazole and 160 mg trimethoprim once a day or 400 mg of sulfamethoxazole and 80 mg of trimethoprim every 12 hours for 10-14 days. The usual dose for children is 40 mg/kg (18.1 mg/lb) sulfamethoxazole and 8 mg/kg (3.63 mg/lb) trimethoprim per 24 hours given in two divided doses every 12 hours for 10 days. This medicine is generally used for a period of 10-14 days for urinary tract infections, 14 days for acute exacerbations of long-term bronchitis, 14-21 days for pneumocystis carinii pneumonia, and 5 days for traveler's diarrhea. This medicine is not known to be addictive or habit-forming.
This medicine should be used on an as-needed basis. Co-Trimoxazole should be used as directed by the doctor even if you feel well, or even if you think that there is no need for you to use your medicine.
Discuss with your doctor if your condition persists or worsens or if you develop new symptoms. Discuss with your doctor if pain or swelling at the injection site, nausea, vomiting, stomach pain, diarrhea, soreness of the mouth, increased sensitivity of skin to the sun, increased or decreased frequency of urination, headache, insomnia, fatigue, dizziness, and ringing in the ears. If you have any kidney disease, For patients with kidney damage, the dose of Co-Trimoxazole should be reduced according to creatinine clearance values. If you have issues with the health of your liver, Co-Trimoxazole should be given with caution to patients who have liver problems.
If you are giving Sulfamethoxazole/Trimethoprim to a child, be sure to use a product that is for use in children. Use the child's weight or age to find the right dose from the product package or medicine label. You can also read the dosage section of this page to know the correct dose for your child. Else, consult with your doctor and follow their recommendation.
If using the liquid form of this medicine, measure the dose using the provided measuring cup, spoon, or dropper. Before pouring the medicine into the measuring device, you should check the measurement markings carefully. Then, pour the dose amount into the device. After use, clean and store the measuring device in a safe place for your next use. You should not use a tablespoon or teaspoon as the dose measuring devices since it can result in an incorrect dose. If indicated on the product package, shake the medicine before use.
Co-Trimoxazole is intended for use into the veins only (intravenous). Co-Trimoxazole should be diluted before the use and is given as an intravenous infusion, a slow injection through a drip into the vein twice a day. An infusion pump may be used for controlling the flow rate of the drip.
Limit drinking alcohol with Co-Trimoxazole.
Your doctor may request that specific lab tests be performed before you start using Sulfamethoxazole/Trimethoprim. Your doctor may ask you to undergo antibacterial-susceptibility test. This test helps the doctor in selecting an appropriate antibacterial drug for starting the therapy.
Medicines may be recommended for uses other than those listed in the medicine guide. You should not use Sulfamethoxazole/Trimethoprim for conditions or symptoms for which it was not prescribed. Do not give Sulfamethoxazole/Trimethoprim to other people, even if they have the same conditions or symptoms that you have. The use of this medicine without the advice of a doctor may cause harm.
Follow storage instructions on the product package if available. Store Sulfamethoxazole/Trimethoprim 20°C-25°C (68°F-77°F), away from moisture, and away from light. Store this medicine away from children and pets.

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How to take Co-Trimoxazole

Your dose may depend on several personal factors. You should consult with your doctor to find out the dose that is best for you. The dose of Co-Trimoxazole depends on the following factors:
  • patient's age
  • patient's weight
  • patient's health
  • the health of the patient's liver
  • the health of the patient's kidneys
  • medicines recommended by your doctor
  • any other medicines in use
  • herbal supplements consumed
  • response to treatment

Co-Trimoxazole Dosage

Dosage for urinary tract infections

Adult
  • Recommended: 800 mg of sulfamethoxazole and 160 mg trimethoprim once a day or 400 mg of sulfamethoxazole and 80 mg of trimethoprim every 12 hours for 10-14 days
Children
  • Recommended: 40 mg/kg (18.1 mg/lb) sulfamethoxazole and 8 mg/kg (3.63 mg/lb) trimethoprim per 24 hours given in two divided doses every 12 hours for 10 days

Dosage for intestinal infection (Shigellosis)

Adult
  • Recommended: 800 mg of sulfamethoxazole and 160 mg trimethoprim once a day or 400 mg of sulfamethoxazole and 80 mg of trimethoprim every 12 hours for 5 days
Children
  • Recommended: 40 mg/kg (18.1 mg/lb) sulfamethoxazole and 8 mg/kg (3.63 mg/lb) trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days

Dosage for worsening of the inflamed lining of bronchial tubes in lungs (acute exacerbations of long-term bronchitis)

Adult
  • Recommended: 800 mg of sulfamethoxazole and 160 mg trimethoprim once a day or 400 mg of sulfamethoxazole and 80 mg of trimethoprim every 12 hours for 14 days

Dosage for serious lung infection in people with weak immune system (pneumocystis carinii pneumonia)

Adult
  • Recommended: 75 to 100 mg/kg (34-45.4 mg/lb) sulfamethoxazole and 15 to 20 mg/kg (6.8-9 mg/lb) trimethoprim per 24 hours given in equally divided doses every 6 hours for 14-21 days
Children
  • Recommended: 75 to 100 mg/kg (34-45.4 mg/lb) sulfamethoxazole and 15 to 20 mg/kg (6.8-9 mg/lb) trimethoprim per 24 hours given in equally divided doses every 6 hours for 14-21 days

Dosage for treatment given to prevent disease (prophylaxis)

Adult
  • Recommended: 1 time in a day
Children
  • Recommended: 750 mg/m2/day sulfamethoxazole and 150 mg/m2/day trimethoprim given in uniformly distributed doses twice a day on three continuous days per week
  • Maximum: 1600 mg sulfamethoxazole and 320 mg trimethoprim per day

Dosage for middle ear infection (acute otitis media)

Children
  • Recommended: 40 mg/kg (18.1 mg/lb) sulfamethoxazole and 8 mg/kg (3.63 mg/lb) trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days

Dosage for infection of digestive tract (traveler's diarrhea)

Adult
  • Recommended: 800 mg of sulfamethoxazole and 160 mg trimethoprim once a day or 400 mg of sulfamethoxazole and 80 mg of trimethoprim every 12 hours for 5 days

Dosage for infectious disease that affects either the lungs or the whole body (nocardiosis)

Adult
  • Recommended: 480 mg-640 mg trimethoprim and 2400 mg-3200 mg sulfamethoxazole once daily for up to 3 months

Minimum Age

infants of 2 months

Dosage calculation for children

To calculate the dosage for children please use the weight based dose calculator to calculate the appropriate dosage as per the weight of your child.

Forms

Tablet
Strength: 800 mg/160 mg and 400 mg/80 mg
Injection
Strength: 400 mg/80 mg
Suspension
Strength: 200 mg/40 mg

Missed Dose

A missed dose should be taken as early as you remember it. However, if the time for the next dose is almost there, then the missed dose should be skipped, and the regular dosing schedule should be continued. Avoid taking a repeated dose to make up for a missed dose.

Overdose

What to do if you overdose on Co-Trimoxazole?
Common sources of therapy include gastric lavage in which the process of cleaning out the Co-Trimoxazole from the stomach occurs, also hemodialysis is slightly effective in eliminating Co-Trimoxazole.
Symptoms of an overdose of Co-Trimoxazole
If you use too much of this medicine, it could lead to dangerous levels of the medicine in your body. In such cases, symptoms of an overdose may include:
If you think you have overdosed on Sulfamethoxazole/Trimethoprim, call a poison control center immediately. You can look up the poison control center information from the Poison Center Finder at TabletWise.com.

Precautions while using Co-Trimoxazole

Before you use Sulfamethoxazole/Trimethoprim, discuss with your doctor if you are allergic to it or its ingredients. Your doctor may prescribe an alternative medicine and update your medical records to record this information. Tell your doctor if you are allergic any of the following substances: trimethoprim, or sulfonamide-antibacterial.
Before you use Co-Trimoxazole, tell your doctor of your medical and health history including the following: reduced count of platelets induced by drugs, lowered red blood cells (megaloblastic anemia), kidney disease, liver disease, an inherited blood disease that may cause skin or nervous system problems (porphyria), birth defect that causes build-up of an amino acid called phenylalanine in the body (phenylketonuria), folate deficiency, inflammation and narrowing of airways of lungs (bronchial asthma), patients with the deficiency of an enzyme (glucose-6-phosphate dehydrogenase), or HIV infection.
The use of this medicine may change potassium. The trimethoprim component of Co-Trimoxazole may result in increased levels of potassium in blood when given to patients with disorders of potassium breakdown, kidney abnormality or when given in combination with drugs that are known to cause an increase in potassium levels. Blood levels of potassium should be closely monitored in such patients. Discontinuation of treatment with Co-Trimoxazole is recommended to help lower the levels of potassium in the blood.
Sulfamethoxazole/Trimethoprim can make you feel sleepy. Be careful when using any machinery, driving a vehicle, or doing any other activity that needs you to be fully alert. The consumption of alcohol with Sulfamethoxazole/Trimethoprim can worsen the sleepiness. Sulfamethoxazole/Trimethoprim may cause rarely seizures in some people. If you perform any activities where a loss of consciousness may cause harm to you (or others), you should discuss with your doctor.
The use of Sulfamethoxazole/Trimethoprim during pregnancy should only be when required. Co-Trimoxazole should be used particularly during the first trimester of pregnancy, only if required. Also, because sulfamethoxazole and trimethoprim may interfere with the breakdown of folic acid, supplementation with folic acid should be considered essential if Co-Trimoxazole is being used during pregnancy. Women who are breastfeeding a baby should not use this medicine. The individual components of Co-Trimoxazole, trimethoprim, and sulfamethoxazole are excreted in human breast milk and can also cause brain damage, induced by excessive bilirubin levels (kernicterus). Also, the use of Co-Trimoxazole in breastfeeding mothers should be avoided who are particularly at risk to develop an abnormal increase of bilirubin in the blood (hyperbilirubinemia). Consult with your doctor on the use of Sulfamethoxazole/Trimethoprim, if you are trying to conceive.
This medicine may increase your sensitivity to sunlight. If this happens, use a sunscreen and cover your skin when you are outdoors. Limit your time in the sun. If you get a sunburn on your skin, consult with your doctor.
Sulfamethoxazole/Trimethoprim may cause increased incidence of side-effects in older patients. Elderly patients may see an increased risk of severe skin reactions, generalized bone marrow suppression, a specific decrease in platelets, high potassium levels in the blood (hyperkalemia), and low level of thrombocytes.

What precautions should be taken during Pregnancy and Nursing, and administering Co-Trimoxazole to Children or the Older Adults?

Pregnant Women

Only When Necessary
Warning: This medicine should be used particularly during the first trimester of pregnancy, only if the potential benefit justifies the potential risk to the fetus.

Breastfeeding

Contraindicated or Not Recommended
Warning: The individual components of Co-Trimoxazole, trimethoprim and sulfamethoxazole are excreted in human breast milk and can also cause kernicterus. Also, the use of Co-Trimoxazole in breastfeeding mothers should be avoided who are particularly at risk to develop an abnormal increase of bilirubin in the blood (hyperbilirubinemia)

Younger Adults Population

Possibly safe
Warning: The use of Co-Trimoxazole is not recommended for children less 2 months in age.

Older Adults Population

Possibly safe
Warning: There is an increased risk of side-effects in elderly patients with damaged kidney and liver function, deficiency of folic acid, or in patients who use other drugs in combination with Co-Trimoxazole.

Co-Trimoxazole Side-effects

The following side-effects may commonly occur when using Sulfamethoxazole/Trimethoprim. If any of these side-effects worsen or last for a long time, you should consult with your doctor:
The following side-effects may commonly occur in older patients on the use of Sulfamethoxazole/Trimethoprim. Discuss with your doctor if any of these side-effects last for a long time or are severe:
  • a specific decrease in platelets
  • bone marrow suppression
  • folic acid deficiency
  • high levels of potassium in the blood
  • severe skin reactions
Rarely, the use of Sulfamethoxazole/Trimethoprim may cause the following side-effects:
The following severe side-effects may also occur when using Sulfamethoxazole/Trimethoprim:
  • immune system disorders (possibly fatal)
    Symptoms: severe skin reaction, life-threatening allergic reactions, inflammation of the heart muscles (allergic myocarditis), skin reaction induced by medicine or infection (erythema multiforme), scaling and peeling of the skin (exfoliative dermatitis), swelling of the lower layer of skin, drug fever, chills, inflammation of small blood vessels, specific drug reactions (blood sickness-like syndrome), sensitivities to substances (generalized allergic reactions), swollen bumps (generalized skin eruptions), increased sensitivity to sunlight (photosensitivity), redness of the eye due to injury or illness (conjunctival and scleral injection), severe itching, hives, rash, swollen arteries (periarteritis nodosa) body's immune system attacks its own tissues (systemic lupus erythematosus)
  • kidney and urinary disorders
    Symptoms: kidney failure, swelling in between the kidney tubules, elevated blood urea nitrogen level, elevated blood creatinine level, kidney disorder associated with low urine output or absence of any urine output, cloudy urine kidney damage
  • brain and mental disorders
    Symptoms: inflammation of the brain and spinal cord membrane, convulsions, weakness, numbness, and pain due to nerve damage, loss of muscle control, vertigo, ringing in the ears, headache, hallucinations, depression, lack of interest (apathy) nervousness
  • musculoskeletal disorders
    Symptoms: joint pain, muscle pain skeletal muscle injury
  • eye disorders (when used inflammation of the middle layer of eye (uvea) |)
  • blood disorders (possibly fatal)
    Symptoms: reduction in the number of white blood cells (granulocytes), decreased production of new blood cells (aplastic anemia), low levels of thrombocytes in the blood, decreased number of white blood cells (leukopenia), low level of neutrophils, premature destruction of red blood cells (hemolytic anemia), lowered red blood cells (megaloblastic anemia), rare blood disorder (hypoprothrombinemia), increased quantities of hemoglobin (methemoglobinemia), increase in the number of eosinophils (eosinophilia), destruction of red blood cells (haemolysis), clotting in small blood vessels, low platelet count imbalancement in body fluids (blood dyscrasias)
  • stomach and intestinal disorders
    Symptoms: hepatitis (including decreased bile flow from liver and sudden liver injury), increased blood transaminase levels, elevated bilirubin levels, inflammation of the large intestine, inflammation in the pancreas, painful swelling and sores inside the mouth, inflammation of the tongue, nausea, emesis, abdominal pain, diarrhea abnormally low body weight
  • metabolic and nutritional disorders
    Symptoms: low sodium levels in the blood, decreased appetite, low blood sugar levels, excessive production of acids in the body high levels of potassium in the blood
  • endocrine disorders
    Symptoms: allergy to two allergens (cross-sensitivity), excessive production of urine low blood sugar levels
  • Symptoms: cough, shortness of breath, collection of pus, blood or protein in the lungs
Your doctor has prescribed Sulfamethoxazole/Trimethoprim because they judge that the benefit is greater than the risk posed by side-effects. Many people using this medicine do not have serious side-effects. This page does not list all possible side-effects of Sulfamethoxazole/Trimethoprim.
If you experience side-effects or notice other side-effects not listed above, contact your doctor for medical advice. You may also report side-effects to your local food and drug administration authority. You can look up the drug authority contact information from the Drug Authority Finder at TabletWise.com.

Side-effects and Allergic Reactions of Co-Trimoxazole by Severity and Frequency

Common Side-effects

Following are the common side-effects of this medicine:

Infrequent and Rare Side-effects

Following are the infrequent and rare side-effects of this medicine:

Severe Side-effects

Following are the severe side-effects of this medicine:

Side-effects in Older Adults

Following are the side-effects of this medicine in elderly patients:
  • a specific decrease in platelets (with or without blood spots)
  • generalized bone marrow suppression
  • hyperkalemia
  • severe skin reactions

Mild Allergic Reactions

Following are the symptoms of mild allergic reactions to this medicine:

Serious Allergic Reactions

Following are the symptoms of serious allergic reactions to this medicine:
possibly fatal
If you experience side-effects or notice other side-effects not listed above, contact your doctor for medical advice. You may also report side-effects to your local food and drug administration authority. You can look up the drug authority contact information from the Drug Authority Finder at TabletWise.com.

Warnings

Severe reactions due to sulfonamides

Patients who are on treatment with sulfonamide-containing drugs such as Co-Trimoxazole are at an increased risk to experience harmful side-effects. Such patients are at an increased risk to experience a rare and severe skin reaction (Stevens-Johnson syndrome), severe liver damage (fulminant liver necrolysis), deficiency of granulocytes in the blood, a condition in which the body stops producing new blood cells (aplastic anemia) and other blood disorders. Reactions such as rashes, fever, sore throat, unhealthy pale appearance (pallor), joint pain (arthralgia), purple or red discolored spots on the skin or yellow discoloration of the skin (jaundice) may be the indications of serious reactions. If patients who are on treatment with sulfonamide-containing drugs such as Co-Trimoxazole develop skin rashes, the use of Co-Trimoxazole should be discontinued.

Low thrombocyte count

Patients using Co-Trimoxazole are at an increased risk to develop a reduced level of thrombocytes. Such patients are at an increased risk to experience severe cases of reduced thrombocyte count that are fatal or life-threatening, which usually disappears when the drug is discontinued.

Severe allergic reactions of the respiratory tract

Patients who are on treatment with Co-Trimoxazole are at an increased risk of severe allergic reactions such as shortness of breath, cough and infectious material in the lungs (pulmonary infiltrates).

Bacterial infections (beta-hemolytic streptococcal infections)

The sulfonamides should not be used to treat group A beta-hemolytic streptococcal infections since they will not remove the streptococcus and prevent the previous infection such as rheumatic fever.

Elderly patients with abnormal functioning of the kidney or liver

Elderly patients who are undergoing treatment with Co-Trimoxazole are at an increased risk to experience severe side-effects due to abnormal functioning of the kidney or liver function. Signs of the presence of crystals in the urine (crystalluria) is rare, although crystals of sulfonamide have been seen in cooled urine of the treated patients. In patients suffering from malnutrition, the risk may be increased. Provide special care and maintain sufficient urinary output at all the times in such patients.

Elderly patients or patients with folic acid deficiency

Patients who have a deficiency of folic acid and elderly patients are at an increased risk to experience asymptomatic changes in laboratory blood tests (hematological laboratory indices) due to lack of folic acid availability. Such changes may be reversed by giving folinic acid (5-10 mg/day) which does not interfere with the antibacterial activity. Regular monitoring of monthly blood counts is advisable when Co-Trimoxazole is given for a long period, or to patients with folic acid deficiency, or the elderly.

Patients with deficiency of an enzyme, glucose-6-phosphate dehydrogenase (G6PD)

Such patients may experience the breakdown of red blood cells (haemolysis).

Patients with inflammation and narrowing of airways (bronchial asthma)

Take the necessary precautions while using this medicine in such patients.

Patients with a birth defect causing an amino acid called phenylalanine to build up in the body (phenylketonuria)

Trimethoprim component of Co-Trimoxazole has been noted to block the breakdown of phenylalanine but this is of no significance in phenylketonuric patients on proper dietary restriction.

Patients with a disorder that affects the nervous system (acute porphyria)

Both trimethoprim and sulfonamides components of Co-Trimoxazole have been related to worsening of porphyria. The use of Co-Trimoxazole in patients with porphyria should be avoided.

Patients at risk of high levels of potassium in the blood

Proper monitoring of potassium levels in the blood should be done in such patients.

Excessive acidic condition of the body fluids or tissues (acidosis)

Patients who are on treatment with Co-Trimoxazole have been associated with metabolic acidosis when other possible causes have been removed. It is advised that proper monitoring should be done when metabolic acidosis is suspected.

Patients with serious blood disorders (hematological disorders)

Co-Trimoxazole should be given to patients with severe hematological disorders only under careful supervision. The drug has also been given to the patients who are on treatment with cytotoxic drugs with little or no effect on the peripheral blood or bone marrow.

Combination of Co-Trimoxazole with other antibiotics

The combination of Co-Trimoxazole with other antibiotics should only be given when the benefits of treatment outweigh any possible risks according to doctor and consideration should be given to the use of a single antibacterial agent which is effective.

Diarrhea due to bacterial growth (Clostridium difficile associated diarrhea)

The patients who are on treatment with Co-Trimoxazole or other antibacterials are at an increased risk to develop mild to fatal diarrhea (Clostridium difficile associated diarrhea) as the treatment with antibacterial agents alters the flora of the intestine which leads to the overgrowth of bacteria C. difficile. In case the diarrhea is suspected in patients undergoing antibacterial therapy, ongoing treatment should be discontinued. Appropriate fluid and electrolyte management, supplementation with protein, treatment of C. difficile with an antibiotic, and surgical evaluation should be instituted as clinically required.

Interactions with Co-Trimoxazole

When two or more medicines are taken together, it can change how the medicines work and increase the risk of side-effects. In medical terms, this is called as a Drug Interaction.
Sulfamethoxazole/Trimethoprim may interact with diuretics like thiazides, which are used to reduce the amount of salt and water in the body. Patients taking both Co-Trimoxazole and diuretics like thiazide may see an increased risk of low levels of thrombocytes with purple or red discolored spots on the skin.
There may be an interaction of Co-Trimoxazole with anticoagulants like warfarin, which are used to prevent blood clotting. The use of Co-Trimoxazole may increase the bleeding time in patients who are on therapy with anticoagulants. Carefully monitor the prothrombin time in patients who are on therapy with anticoagulants and Co-Trimoxazole.
Sulfamethoxazole/Trimethoprim interacts with phenytoin, which is used for the treatment of seizures. Co-Trimoxazole is known to prevent the breakdown of phenytoin in the liver. When Co-Trimoxazole is given at a recommended dose, the blood levels of phenytoin were found to increase, and the clearance was decreased. When Co-Trimoxazole is given in combination with phenytoin, the possible effects of phenytoin should be known.
Special instructions need to be followed while taking this medicine along with methotrexate, which is used to treat cancer and as an immunosuppressant. Sulfonamides such as Co-Trimoxazole can replace methotrexate from its protein binding sites in the blood and also competes with the transport of methotrexate in kidneys, which can result in increased levels of free methotrexate. cyclosporine, which is used to prevent organ rejection during transplantation procedure.
Your doctor's guidelines may need to be followed while taking this medicine along with When Co-Trimoxazole is used along with cyclosporin, the patients who have undergone kidney transplant may experience reversible kidney damage. The levels of digoxin in the blood may get increased when given in combination with Co-Trimoxazole, particularly in elderly patients. The levels of digoxin in blood should be monitored.
Sulfamethoxazole/Trimethoprim may interact with indomethacin, which is used to treat pain, fever, and inflammation. The levels of sulfamethoxazole, one of the components of Co-Trimoxazole may get increased in patients taking indomethacin.
There may be an interaction of Co-Trimoxazole with pyrimethamine, which is used to treat parasitic infections. The patients who receive pyrimethamine to prevent malaria at a dose exceeding 25 mg a week may develop unusually large, structurally abnormal, and immature red blood cells (megaloblastic anemia) if Co-Trimoxazole is prescribed.
Sulfamethoxazole/Trimethoprim interacts with tricyclic antidepressants, which is used for the treatment of depression. The effectiveness of tricyclic antidepressants decreases when given with Co-Trimoxazole.
Special instructions need to be followed while taking this medicine along with oral hypoglycemics like repaglinide, which are used to lower high blood glucose levels. Like other drugs that contain sulfonamide, Co-Trimoxazole also enhances the effect of oral hypoglycemics.
Your doctor's guidelines may need to be followed while taking this medicine along with amantadine, which is used for the treatment of viral infections and Parkinson's disease. When Co-Trimoxazole was given in combination with amantadine, a single case of delirium which is characterized by restlessness, illusions, and incoherence (delirium) has been reported in the literature.
Sulfamethoxazole/Trimethoprim may interact with angiotensin-converting enzyme inhibitor, which is used for the treatment of high blood pressure and heart failure. When Co-Trimoxazole was used in combination with angiotensin-converting enzyme inhibitor, three cases of high levels of potassium in the blood in elderly patients have been reported in the literature.
There may be an interaction of Co-Trimoxazole with drug and laboratory test. The trimethoprim component of Co-Trimoxazole can interfere with the blood methotrexate assay, which is determined by the competitive binding protein technique when an enzyme, bacterial dihydrofolate reductase is used as the binding protein. No interference occurs, however, if a radioimmunoassay technique determines methotrexate. The two components of Co-Trimoxazole may also interfere with the reaction assay used for creatinine, resulting in overestimations of average values.
Sulfamethoxazole/Trimethoprim interacts with zidovudine and lamivudine, which is used to prevent and treat HIV/AIDS. Use of Co-Trimoxazole with zidovudine increases the risk of blood-related side effects and when Co-Trimoxazole is used in combination with lamivudine increases the exposure of lamivudine because of the trimethoprim component of Co-Trimoxazole. If the treatment with these drugs is important, monitoring of blood parameters should be done.
Special instructions need to be followed while taking this medicine along with procainamide, which is used to treat irregular heart rhythm. When trimethoprim is taken along with drugs that form cations at physiological pH, and are partly excreted by kidneys (e.g., procainamide, amantadine), there is the possibility of prevention of this process which may increase the levels of one or both the drugs.
Your doctor's guidelines may need to be followed while taking this medicine along with folinic acid, which is used to decrease the harmful effects of methotrexate and pyrimethamine. Supplementation with folinic acid has been shown to interfere with the antimicrobial effectiveness of Co-Trimoxazole.
This page does not contain all the possible interactions of Sulfamethoxazole/Trimethoprim. Share a list of all medicines that you use with your doctor and pharmacist. Do not start, stop, or change the dose of any medicines without the approval of your doctor.

Interactions of Co-Trimoxazole by Severity

Serious

The following medicines may interact when taken together and can cause harmful effects in the body. Please consult with your doctor or pharmacist before taking these medicines together.

Moderate

The following medicines may interact when taken together and can increase your risk of harmful effects. Please consult with your doctor or pharmacist before taking these medicines together.

When should Co-Trimoxazole be not used?

Allergic to trimethoprim or sulfonamides

This medicine is not recommended for patients who are allergic to Co-Trimoxazole.

Patients with a history of drug-induced low levels of thrombocytes

Avoid the use of Co-Trimoxazole in patients with a previous history of drug-induced low levels of thrombocytes.

Pregnant women and breastfeeding mothers

Co-Trimoxazole should not be given to pregnant women and breastfeeding mothers as Co-Trimoxazole passes into the placenta and is excreted in the milk and may cause brain damage due to excessive jaundice (kernicterus).

Children aged less than 2 months

Do not use this medicine in children aged less than two months.

Patients with liver damage

This medicine is not recommended for use in patients with abnormal functioning of the liver.

Patients with kidney damage

Co-Trimoxazole should not be given to patients who have kidney damage and in patients in whom regular monitoring of blood cannot be done.

Patients with acute porphyria (rare metabolic disoder)

Avoid the use of Co-Trimoxazole in patients with acute porphyria.

Traveling With Medication

  • Ensure that you carry enough doses of each of your prescription medicines to last the entire trip. The best place to store your medicines is in the carry on baggage. However, while flying, if carrying liquid medicines, make sure you do not go over the limits imposed for carry-on liquids.
  • While traveling overseas, make sure that you can carry each of your prescription medicines legally to your destination country. One way to ensure this is by checking with your destination country's embassy or website.
  • Make sure that you carry each of your medicines in their original packaging, which should typically include your name and address, and the details of the prescribing doctor.
  • If your travel involves crossing time zones, and you are required to take your medicine as per a fixed schedule, make sure that you adjust for the change in time.

Expired Medication

Taking a single dose of expired Co-Trimoxazole is unlikely to cause a side-effect. However, please discuss with your doctor or pharmacist, if you feel unwell or sick. An expired medicine may become ineffective in treating your prescribed conditions. To be on the safe side, it is important not to use an expired drug. You are much safer by always keeping a fresh supply of unexpired medicines.

Safe Disposal of Medication

  • If there are disposal instructions on the package, please follow the instructions.
  • If there are medicine take-back programs in your country, you should contact the respective authority to arrange for the disposal of the medicine. For example, in the USA, the Drug Enforcement Administration regularly hosts National Prescription Drug Take-Back events.
  • If there are no take-back programs, mix the medicine with dirt and place them in a sealed plastic bag. Throw the plastic bag in your household trash. Separately, remove all personal information including the prescription label from the medicine packaging and then dispose off the container.
  • If specifically indicated on the medicine package that it needs to be flushed down the toilet when no longer needed, perform the required step.
This page provides information for Sulfamethoxazole/Trimethoprim .
Urinary Tract Infections
Ear Infections
Chronic Bronchitis
Trimethoprim/sulfamethoxazole - 1 learning sets

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