If I vomited half an hour after taking oseltamivir, should I take another dose?

Generally, whether to take an additional dose of oseltamivir after vomiting half an hour post-administration depends on the specific circumstances. If no intact tablet is found in the vomit and the vomiting is mild, taking another dose may be considered. However, if vomiting is severe or undissolved medication is present, re-dosing is generally not recommended. If in doubt, it is advisable to consult a healthcare professional in advance. Detailed analysis is as follows:

If no intact tablet is observed in the vomit and the vomiting is mild (only one episode without persistent nausea), and the medication was taken for treating influenza (especially within 48 hours of symptom onset), some drug absorption may have already occurred, although likely insufficient. In such cases, a supplementary half or full dose may be taken under the guidance of a doctor or pharmacist to avoid compromising treatment efficacy.

If an intact tablet is visible in the vomit, or if vomiting is severe (repeated episodes accompanied by abdominal pain), or if the medication was taken for influenza prophylaxis, the drug was likely not absorbed or only minimally absorbed. However, repeated dosing may increase gastrointestinal burden and lead to further discomfort; therefore, immediate re-dosing is generally not advised. Instead, continue with the next scheduled dose as originally planned.

After vomiting following oseltamivir administration, carefully observe the vomit and your overall condition. It is best to consult a healthcare professional before deciding on re-dosing—do not make the decision independently. If vomiting persists or other adverse symptoms occur, seek medical attention promptly to adjust the treatment regimen and ensure safe and effective medication use.