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Why it's used

Ondansetron is used for the management of nausea and vomiting induced by cancer treatment through anticancer drugs and radiation in adults and children. This medicine works by blocking the release of serotonin, a natural substance which may cause vomiting and nausea. Ondansetron is also used to prevent nausea or vomiting occurring after a surgical procedure.
When not to use
Ondansetron should not be used to treat patients with a genetic disorder characterized by prolonged heartbeat (congenital long QT syndrome).
Serotonin-3 Receptor Antagonist
Ondansetron is a prescription medicine that belongs to a class of medicines called Serotonin-3 Receptor Antagonist. Serotonin type 3 (5-HT3) receptor antagonists are used for prevention of post-surgical or chemotherapy-induced nausea and vomiting. They are also as a therapy for diarrhea-predominant irritable bowel syndrome.

How to use

Read the directions on the product label, patient guide, or medicine guide provided by the medicine company or your pharmacist before starting to use Ondansetron. If you have any questions related to this medicine, ask your doctor or pharmacist. Consume this medicine as recommended by your doctor.
Ondansetron is consumed with or without food. Absorption of Ondansetron increases in the presence of food and unaffected by antacids. While taking a Ondansetron orally disintegrating (ODT) tablet, you should immediately place it with dry hands on the top of the tongue and swallow with saliva. It is not necessary to take Ondansetron ODT tablet with water.
The typical dose of Ondansetron is 8 mg of Ondansetron 30 minutes before starting radiotherapy or chemotherapy, followed by 8 mg dose 8 hours after the first dose. The usual dose for children is for 12-17 years of children, 8 mg is given 30 minutes before the start of the therapy, followed by 8 mg dose 4 and 8 hours after the first dose, followed by 8 mg thrice a day after completion of therapy. For patients of 4-11 years, 4 mg is given 30 minutes before the start of therapy, followed by 4mg dose 4 and 8 hours after the first dose, then 4 mg dose given thrice a day for 1 to 2 days after completion of chemotherapy. Ondansetron is commonly used at the same time every day. If you have been prescribed Ondansetron for chemotherapy, then you have to use this medicine at the same time on every chemo cycle. This medicine is not known to be habit-forming.
You should continue to use this medicine as directed by the doctor even if you feel well.
Talk to your doctor if your condition persists or worsens or if you develop new symptoms. Tell your doctor if hallucinations, loss of coordination, seizures, and loss of consciousness (coma). You should consult with your doctor before stopping the use of Ondansetron.
A lower dose might be recommended for women. This is because Ondansetron is removed from the body in women more slowly than in men.
If you are giving Ondansetron to a child, be sure to use a product that is meant for children. Before giving this medicine to a child, use the child's weight or age to find the right dose from the product package. 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 orally-disintegrating form of this medicine, make sure you do not consume any food or fluid 5 minutes before or after taking this medicine. Before taking the medicine out of the package, wash your hands thoroughly. Place the medicine on the tongue. Make sure you do not chew or swallow the medicine. You do not need to drink water after consuming the medicine. In certain cases, the medicine can taste slightly bitter. Also, ensure that you do not break or split the medicine.
Ondansetron injection is usually given into a muscle (intramuscular) or a vein (intravenous ). A single dose of 32 mg should be infused over 15 minutes starting before 30 minutes of emetogenic chemotherapy. Before giving Ondansetron injection to the patient, it should be diluted in 50 mL of 5% dextrose injection or 0.9% sodium chloride injection.
Ondansetron is known to be safe with alcohol.
You should store Ondansetron room temperature, away from moisture, and away from light. Store the medicine away from the reach of children and pets.
Medicines may be prescribed for uses other than those listed in the medicine guide. Do not use Ondansetron for conditions for which it was not prescribed. Do not give Ondansetron to other people who might have the same conditions or symptoms that you have. Self-medication may harm them.
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How to take Ondansetron

Your dose and how often you take Ondansetron will depend on the following factors:
  • age
  • gender
  • weight
  • patient's health
  • medicines recommended by the doctor
  • any other medicines being used
  • herbal supplements in use
  • response to the medicine

Ondansetron Dosage

Dosage for nausea and vomiting induced by cancer chemotherapy, including cisplatin greater than or equal to 50 mg/m2

Adult
  • Recommended: 24 mg before 30 minutes of starting single-day highly emetogenic chemotherapy
Children (6 months to 18 years)
  • Recommended: three doses of 0.15 mg/kg (0.07 mg/lb), the first dose is to be given 30 minutes before the start of chemotherapy, followed by 0.15 mg/kg (0.07 mg/lb) given 4 and 8 hours after the first dose

Dosage for nausea and vomiting related with initial and repeat courses of adequate emetogenic cancer chemotherapy

Adult
  • Recommended: 8 mg twice a day, every 12 hours for 1 to 2 days after completion of chemotherapy
  • Initial: 8 mg given 30 minutes before the start of chemotherapy followed by 8 mg dose after 8 hours of the first dose
Children (12-17 years)
  • Recommended: 8 mg thrice a day for 1-2 days after completion of chemotherapy
  • Initial: 8 mg given 30 minutes before the start of chemotherapy, followed with 8 mg dose 4 and 8 hours after the first dose
Children (4-11 years)
  • Recommended: 4 mg thrice a day for 1-2 days after completion of chemotherapy
  • Initial: 4 mg given 30 minutes before the start of chemotherapy, followed by 4 mg dose 4 and 8 hours after the first dose
Children (6 months to 18 years)
  • Recommended: three doses of 0.15 mg/kg (0.07 mg/lb), the first dose is to be given 30 minutes before the start of chemotherapy, followed by 0.15 mg/kg (0.07 mg/lb) given 4 and 8 hours after the first dose

Dosage for nausea and vomiting related with high doses of radiation (radiotherapy) in patients having total body exposure to radiation (irradiation)

Adult
  • Recommended: 8 mg given 1 to 2 hours before undergoing each fraction of radiotherapy every day

Dosage for nausea and vomiting related with single high-dose fraction radiotherapy to the stomach

Adult
  • Recommended: 8 mg is taken 1-2 hours before radiotherapy, followed by 8 mg doses every 8 hours after the first dose for 1-2 days after completion of radiotherapy

Dosage for nausea or vomiting occurring after a surgical operation (postoperative nausea and/or vomiting)

Adult
  • Recommended: 16 mg given 1 hour before the start of temporary loss of sensation (anesthesia)
Children (infants and children of 1 month to 12 years (weighing 40 kg or less))
  • Recommended: 0.1 mg/kg (0.04 mg/lb) as a single dose injected directly into veins
Children (infants and children of 1 month to 12 years (weighing more than 40 kg))
  • Recommended: 4 mg as a single dose

Dosage for nausea and vomiting related with daily fractionated radiotherapy to the stomach

Adult
  • Recommended: 8 mg given 1 to 2 hours before radiotherapy, followed by 8 mg doses every 8 hours after the first dose of radiotherapy for each day

Minimum Age

1 month

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

Tablets
Strength: 4 mg, 8 mg
Orally disintegrating tablets
Strength: 4 mg and 8 mg
Oral solution
Strength: 4 mg/5 mL, 2 mg, and 4 mg
Liquid
Strength: 2 mg
Injection
Strength: 2 mg/1ml and 32 mg/50ml
Film, soluble
Strength: 4 mg and 8 mg
Tablet, film coated
Strength: 4 mg, 8 mg, 16 mg, and 24 mg

Missed Dose

In case of a missed dose, take it as soon as you remember. If it is the time of the next dose, take the next regular dose but do not take the double dose in order to make up for the missed dose.

Overdose

What to do if you overdose on Ondansetron?
As no specific antidote is available for Ondansetron, the supportive therapy and treatment according to symptoms should be given to such patients. The use of ipecacuanha is not recommended in such patients.
Symptoms of an overdose of Ondansetron
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:
  • a sudden drop in heart rate with abnormal electrical conduction of the heart (a vasovagal episode with transient second-degree heart block)
  • abnormally rapid breathing (tachypnea)
  • anxiety (agitation)
  • dilation of the pupil of the eye
  • drowsiness
  • excessive sweating (diaphoresis)
  • high blood pressure
  • low blood pressure
  • overactive reflexes (hyperreflexia)
  • rapid heart rate
  • redness of the skin (flushing)
  • seizures
  • severe constipation
  • sudden blindness (amaurosis)
  • sudden muscle contractions (myoclonic movements)
  • uncontrolled eye movements (horizontal nystagmus)
If you think you have overdosed on Ondansetron, 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 Ondansetron

Before you use Ondansetron, 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: granisetron, dolasetron, alosetron, or palonosetron.
Before you use Ondansetron, tell your doctor of your medical and health history including the following: irregular heart beat, heart failure, low blood levels of magnesium, low blood levels of potassium, prolonged heartbeat (long QT syndrome), liver problems, genetic birth defect causing the build-up of an amino acid in the body (phenylketonuria), or severe constipation. Before having surgery during the use of Ondansetron, discuss with your doctor and dentist about the medicinal products you use including prescription/non-prescription/herbal medicines.
The use of this medicine may change Electrocardiogram (ECG) monitoring. Electrocardiogram (ECG) changes including QT interval prolongation have been seen in patients receiving Ondansetron.
Ondansetron 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 Ondansetron can worsen the sleepiness. Ondansetron 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 Ondansetron is known to be not safe for use in pregnant women. If you are planning to become pregnant or are currently pregnant, you should discuss with your doctor the potential impact of this medicine on the baby before you start to using it. There is no appropriate data available on the safety of Ondansetron during pregnancy. The use of Ondansetron is not safe for use in women who are breastfeeding. If you are breastfeeding a baby, discuss with your doctor if you should either discontinue breastfeeding or stop using this medicine while breastfeeding. Consult with your doctor on the use of Ondansetron, if you are trying to conceive.
Ondansetron is known to be safe with alcohol.

Ondansetron Side-effects

The following side-effects may commonly occur when using Ondansetron. If any of these side-effects worsen or last for a long time, you should consult with your doctor:
Rarely, the use of Ondansetron may cause the following side-effects:
  • chest pain (angina)
  • cold sensation
  • dizziness
  • fainting
  • female reproductive organ disorders (gynecological disorders)
  • hives
  • increased levels of liver enzymes (aspartate transaminase (AST), alanine transaminase (ALT), and transaminase)
  • involuntary contractions of the diaphragm (hiccups)
  • muscle pain (musculoskeletal pain)
  • palpitation
  • shivers
  • transient blindness
The following severe side-effects may also occur when using Ondansetron:
  • eye disorders
    Symptoms: blurred vision temporary blindness
  • central nervous system disorders (neurological disorders)
    Symptoms: headache, involuntary muscle contractions, seizures, prolonged involuntary upward deviation of the eyes (oculogyric crisis) dizziness
  • liver disorders (possibly fatal)
    Symptoms: liver failure
  • allergic reactions
    Symptoms: wheezing, chest tightness, swelling of eyelids, facial swelling, swelling of the lips, swelling of the mouth, swelling of the tongue, swelling of throat, difficulty in breathing, skin rash, seizures, temporary loss of vision, low blood pressure swelling of the lower layer of skin
    If this happens, discontinue the use of this medicine and contact your doctor right away.
  • heart disorders
    Symptoms: chest pain, electrocardiograph changes, sudden loss of heart function, breathing and consciousness (cardiopulmonary arrest), increased heartbeat, irregular heartbeat (atrial fibrillation), shock, abnormal heartbeat (arrythmia), slow heartbeat (bradycardia) palpitation
    If this happens, discontinue the use of this medicine and contact your doctor right away.
Your doctor has prescribed this Ondansetron because they have judged that the benefits outweigh the risks posed by side-effects. Many people using this medicine do not have serious side-effects. This is not a complete list of possible side-effects for Ondansetron.
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

Incomplete absorption of glucose-galactose (Lapp lactase deficiency or galactose intolerance)

As Ondansetron contains lactose and therefore patients with galactose intolerance should not take this medicine.

Liver problems

Patients with liver problems should consult with the doctor. Also, for children who are on Ondansetron treatment in combination with chemotherapeutic agents having damaging effects on the liver should be monitored closely for any damage to the liver.

Masking of bleeding

Patients who have undergone the surgical procedure for removal of adenoids (patch of tissues behind the nose), for the prevention of nausea and vomiting with Ondansetron are at an increased risk of masking of bleeding. Such patients should be carefully monitored after giving Ondansetron.

Time taken for food to travel through the digestive tract (bowel transit time)

Patients with signs of subacute prevention of passage of digested food through the bowel (intestinal obstruction) should be monitored following dosage, as Ondansetron increases the large bowel transit time.

Genetic birth defect causing the build-up of an amino acid in the body (phenylketonuria)

Patients with phenylketonuria should be informed that Ondansetron orally disintegrating tablets contain phenylalanine, which is a component of sweetener.

Masking of progressive bloating of the stomach (ileus and gastric distension)

Patients using Ondansetron after the stomach surgery or in patients with chemotherapy-induced nausea and vomiting may mask a progressive ileus and gastric distension. Monitoring of decreased bowel activity, particularly in patients who are at an increased risk for stomach and intestinal blockage is recommended. Ondansetron should not be used to activate a series of muscle contractions in the digestive tract (gastric or intestinal peristalsis).

Life-threatening syndrome induced by use of serotonergic drugs (serotonin syndrome)

Patients who are on treatment with certain medicines (histamine receptor antagonists, serotonin reuptake inhibitors, serotonin, and norepinephrine reuptake inhibitors) are at an increased risk to develop serotonin syndrome which can be fatal in some cases. The syndrome has also occurred in patients after inducing a temporary loss of sensation (anesthesia) or in an infusion center. These patients may develop symptoms such as agitation, hallucinations, delirium, coma, increased heartbeat, sudden rise in blood pressure, dizziness, sweating (diaphoresis), flushing, increased body temperature, tremor, rigidity, sudden muscle contraction (myoclonus), overactive reflexes (hyperreflexia), incoordination, seizures, nausea, vomiting, or diarrhea. Such patients should be carefully monitored for the development of serotonin syndrome, occurring most commonly with the use of Ondansetron and other serotonergic drugs together. If any symptom of serotonin syndrome appears, the use of Ondansetron should be discontinued, and supportive treatment should be started.

Abnormal heartbeat (QT prolongation)

Patients consuming Ondansetron are at increased risk of developing abnormal heartbeat (QT prolongation). Avoid the use of Ondansetron in patients with abnormal heartbeat (congenital QT prolongation). An ECG monitoring is recommended in patients with congestive heart failure, slow heartbeat, electrolyte abnormalities, and abnormal heart rhythms.

Severe allergic reactions

Patients who are allergic to Ondansetron are at an increased risk when using this medicine. Such patients may have an increased risk of developing allergic reactions such as life-threatening allergic reaction (anaphylaxis) and tightening of the muscles of the lungs (bronchospasm). If such allergic reactions occur, the use of Ondansetron should be discontinued, and the patient should be monitored carefully until the signs and symptoms go away.

Interactions with Ondansetron

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.
Ondansetron may interact with serotonergic drugs, which are used to treat depression. The use of Ondansetron with serotonergic drugs may cause a life-threatening condition caused by the use of serotonergic drugs (serotonin syndrome). Such patients may experience symptoms like mental status changes, autonomic instability (e.g., high blood pressure, neuromuscular symptoms (e.g., tremor, rigidity), seizures, stomach and intestine symptoms (e.g., nausea, vomiting, diarrhea). Patients should be monitored for the exposure of serotonin syndrome. If any of these symptoms occur, discontinue the use of Ondansetron and provide supportive treatment.
There may be an interaction of Ondansetron with drugs affecting cytochrome P-450 enzymes (cyto3A4, cyto2D6, cyto1A2), which helps in the metabolism of the drug. The use of Ondansetron with cytochrome P3A4 inducers such as (phenytion, carbamazepine, rifampin) may decrease the level of Ondansetron in the blood. There is no requirement for dosage adjustment of Ondansetron in such patients.
Ondansetron interacts with tramadol, which is used to help relieve moderate to adequately severe pain. When Ondansetron is used in combination with tramadol, Ondansetron may reduce the pain-relieving effect of tramadol. Such patients should be monitored to ensure adequate pain control.
Special instructions need to be followed while taking this medicine along with apomorphine, which is used to treat Parkinson's disease. The use of Ondansetron with apomorphine may cause low blood pressure and loss of consciousness in the patients. The use of Ondansetron with apomorphine is not recommended.
Your doctor's guidelines may need to be followed while taking this medicine along with drugs that cause prolonged heartbeat (QT prolonging drugs). When Ondansetron is used with QT-prolonging drugs (such as doxorubicin, daunorubicin, trastuzimab, erythromycin, ketoconazole, amiodarone, atenolol or timolol) may increase the risk of irregular heartbeat. Take necessary precautions while taking Ondansetron with QT-prolonging drugs in such patients.
This page does not contain all the possible interactions of Ondansetron. 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.

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 Ondansetron 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.

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