Welcome to Ask The Doctor.
I understand your concern.
Reheated coffee or tea of long duration should not be used as these products are prepared from milk and it can get contaminated if kept for long and can cause stomach upset and infection. So, it should be avoided.
Share my opinion with your doctor.
I hope it helps.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.