Zofran typically starts to work within 30 minutes to 2 hours after taking a dose. The onset time depends on the formulation: orally disintegrating tablets (ODT) usually work faster, often within 15 to 30 minutes, while oral tablets might take longer as they need to be digested. Injectable forms work quickest, often within 15 minutes. Factors like age, metabolism, dosage, and other medications can also influence how fast Zofran takes effect. Generally, full effect is reached within about 2 hours. References:

• Orally disintegrating tablets work in 15-30 minutes; oral tablets around 30 minutes to 2 hours; injections in about 15 minutes.

• Metabolism, age, and other medications might affect onset.

• Recommended to take Zofran ahead of expected nausea for best effect.