Ondansetron

5-HT3 antagonist

Also sold as Zofran

Onset of effect

30 min – 1 hr

Felt/clinical effect

Tmax (peak blood level)

1.5 hr – 2 hr

Pharmacokinetic peak

Duration of effect

8 hr – 12 hr

Per single dose

Effect timeline

Approximate single-dose timeline. Onset shows when effects are felt; Tmax shows when blood levels peak.

4 hr8 hr

Onset of effectTmax (peak blood level)Wears off

Notes

QT prolongation at high doses.

What this is

Ondansetron is a 5-ht3 antagonist given by the oral route. It's typically used in the antiemetic category.

What the numbers mean

After one oral dose you'd typically start noticing the effect in 30 min – 1 hr. The drug reaches its highest blood level in about 1.5 hr – 2 hr, and a single dose usually keeps working for around 8 hr – 12 hr.

Practical tips

Swallow with water; check the label for food restrictions.

Important

Don't combine with other products in the same drug class without checking with a pharmacist. Stop and seek medical advice if you have an unexpected reaction, severe side effect, or symptoms that don't improve.

All timings are approximate population ranges for a typical adult dose. Individual response varies with age, genetics, formulation, food, and other medications.

Typical dosing

Source: OpenFDA drug label · adult dosing unless noted

Doses vary by age, weight, kidney/liver function, and indication. Don't change your dose without talking to your prescriber.

Verify on the exact label used:DailyMed search·OpenFDA record

Side effects & warnings

Source: OpenFDA drug label

Verify on the exact label used:DailyMed search·OpenFDA record

Educational information only — not medical advice. Times vary by person, dose, and formulation. Always consult a doctor or pharmacist for personal guidance.