Is it safe for a kidney transplant patient to take tamiflu (oseltamivir) during a flu attack?

Yes. The dose may need adjustment depending on the function of the kidney transplant.
Yes. Tamiflu (oseltamivir) is ok. Tamiflu (oseltamivir) is not known to interact with any of the immunosuppressant medications. It has not been reported to have caused any unique problems in transplant recipients. However, the dose may need to be reduced from 75 mg twice daily to 75 mg once daily if your kidney function is 30 ml/min or less. Also, remember to never take a live flu virus vaccine - it may be too strong for your immune system!