Kytril (Granisetron)

What granisetron is and how it works

Granisetron is a serotonin-3 (5-HT3) receptor antagonist used to prevent and treat nausea and vomiting associated with chemotherapy, radiotherapy, and surgery. It is available as oral tablets, intravenous injection, transdermal patch, and extended-release injection. (1) (2) (3) (4) (5) (6)

Granisetron is typically administered by a healthcare professional in chemotherapy, radiotherapy, or surgical settings. Oral tablets are taken on a prescribed schedule around chemotherapy days. The transdermal patch is applied before chemotherapy and worn for several days. Use only as directed by the prescriber; do not change the dose or schedule without medical advice.

Mechanism of action: how granisetron works

Granisetron is a selective 5-HT3 receptor antagonist. It blocks serotonin receptors in the chemoreceptor trigger zone and vagus nerve, preventing nausea and vomiting triggered by chemotherapy, radiotherapy, or surgery. (1) (2) (4) (5) (6)

What granisetron is used for

Before taking granisetron

Do not take / not appropriate for

• Do not use granisetron if you have a known hypersensitivity to granisetron or any ingredient in the formulation. (all products) (1) (2) (4) (5) (6)

Tell your clinician about

• Any history of heart problems, including arrhythmias or cardiac conduction disorders.
• Any current electrolyte abnormalities (e.g., low potassium or magnesium).
• All medications you are taking, especially those that can affect heart rhythm (e.g., antiarrhythmics, certain antibiotics, antipsychotics) or increase serotonin (e.g., SSRIs, SNRIs, MAOIs, tramadol, St. John’s wort).
• If you are pregnant, think you may be pregnant, or are breastfeeding.
• Any previous hypersensitivity reaction to other 5-HT3 antagonists (e.g., ondansetron, dolasetron).
• If you have liver problems or have been told you have elevated liver enzymes.

How to take granisetron

• Granisetron is administered either as an intravenous injection by a healthcare professional, as an oral tablet taken by the patient, or via a transdermal patch applied to the skin.
• The dose and schedule depend on the type of treatment (chemotherapy, radiotherapy, or surgery) and the formulation used.
• Do not change the dose, frequency, or stop treatment without consulting your doctor.
• For oral tablets: take exactly as prescribed, usually 2 mg once daily or 1 mg twice daily around chemotherapy days.
• For the transdermal patch (Sancuso): apply as directed before chemotherapy and leave in place for the prescribed duration. Remove the old patch before applying a new one.

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

Contact your healthcare provider for advice if you miss a scheduled dose. Do not take an extra dose to make up for a missed one.

Overdose

If you think you have received too much granisetron, seek emergency medical attention immediately. Symptoms of overdose may include headache, dizziness, or fainting.

Side effects

Side effects may vary depending on the indication and formulation. The most common side effects include headache and constipation.

Serious warnings

Interactions

Pregnancy, breastfeeding, kidney/liver function, age

Monitoring

Before starting

• Assess cardiac history, including any arrhythmias or conduction disorders, and document concurrent medications that may prolong the QT interval.
• Check electrolyte levels (potassium, magnesium) and correct if necessary.
• Review all medications for potential serotonergic activity and consider the risk of serotonin syndrome.
• Confirm the appropriate indication and dosing regimen based on the treatment type (chemotherapy, radiotherapy, or surgery) and the selected formulation.

During treatment

• Monitor for signs and symptoms of QT prolongation (e.g., palpitations, syncope); perform ECG if clinically indicated.
• Watch for serotonin syndrome (mental status changes, autonomic instability, neuromuscular hyperactivity); discontinuation of granisetron if suspected is clinician-directed, with supportive care instituted.
• Observe for hypersensitivity reactions; discontinuation immediately if anaphylaxis occurs is clinician-directed.
• For patients on oral or transdermal therapy, assess antiemetic efficacy and skin site integrity (patch).

Storage

Store at room temperature away from moisture and heat. Keep the transdermal patch in its sealed pouch until ready to use. Follow the specific storage instructions on the product label.

Frequently asked questions

References

1. GRANISETRON HYDROCHLORIDE injection — prescribing informationU.S. Food and Drug Administration · United States · accessed 2026-07-30 · source 1
2. Kytril 1mg/2mg film-coated tablets and Granisetron 1mg/mL injection — Summary of Product Characteristicselectronic Medicines Compendium (UK) · United Kingdom · accessed 2026-07-30 · source 2
3. Sancuso (granisetron transdermal patch) — European Public Assessment ReportEuropean Medicines Agency · European Union · dated 2012 · accessed 2026-07-30 · source 3
4. KYTRIL (granisetron hydrochloride) tablets and injection — Product MonographHealth Canada · Canada · accessed 2026-07-30 · source 4
5. KYTRIL granisetron injection and tablets — Australian Product Information (via medsinfo.com.au)Therapeutic Goods Administration · Australia · accessed 2026-07-30 · source 5
6. Granisetron Kabi and Granirex injection — New Zealand Data SheetsMedsafe, New Zealand Medicines and Medical Devices Safety Authority · New Zealand · accessed 2026-07-30 · source 6

Brand names by country

Single-ingredient granisetron names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries