The typical adult dosage of Zofran (ondansetron) is 8 mg taken every 8 to 12 hours

. The frequency of taking Zofran depends on the reason for taking it and other medications you may be taking

. Zofran Dosage:

• Chemotherapy-induced nausea and vomiting For moderate nausea and vomiting, take an 8 mg tablet 30 minutes before chemotherapy, followed by another 8 mg dose 8 hours later. After completion of chemotherapy, take 8 mg every 12 hours for 1 to 2 days

. For severe nausea and vomiting, a single 24-mg dose should be taken 30 minutes before the start of a single day of highly emetogenic chemotherapy

• Radiation therapy Take 8 mg 1 to 2 hours before radiation therapy. After the first dose, 8 mg every 8 hours is recommended, depending on the type and location of the radiation

. For total body irradiation, take 8 mg 1 to 2 hours before each fraction of radiotherapy each day. For single high-dose fraction radiotherapy to the abdomen, take 8 mg 1 to 2 hours before radiotherapy, with subsequent 8-mg doses every 8 hours after the first dose for 1 to 2 days after completion of radiotherapy. For daily fractionated radiotherapy to the abdomen, take 8 mg 1 to 2 hours before radiotherapy, with subsequent 8-mg doses every 8 hours after the first dose for each day radiotherapy is given

• Post-operative nausea and vomiting 16 mg should be administered 1 hour before anesthesia

• Children For children ages 12 to 17, the dosage is the same as for adults. Children ages 4 to 11 should be given 4 mg 30 minutes before the start of chemotherapy, with subsequent 4 mg doses 4 and 8 hours after the first dose. Then, administer 4 mg three times a day for 1 to 2 days after completion of chemotherapy

. Do not give Zofran to children younger than 4 years old

If you have a Child-Pugh score of 10 or greater, do not exceed a total daily dose of 8 mg