Have been using expired Tamiflu what is the side effects?

Using expired Tamiflu (oseltamivir) may reduce its effectiveness, but it is generally not considered harmful. Potential side effects of Tamiflu include nausea, vomiting, diarrhea, headache, and dizziness. If you experience any unusual symptoms after taking expired medication, it's best to consult a healthcare professional for advice. Always check the expiration date before using any medication.