I have a rash on my neck for about 1 week red blotches woke now a rash on my upper right side i have been very tired and taking phentermine?

Drug rash: Based on what we know, the most logical step would be to stop the Phentermine and see if the rash goes away and stays away. Any drug can cause a rash. Otherwise, someone will actually need to see the rash in order to be able to help you.

Unsure: This rash would likely need to be examined and more history obtained to be able to provide you with useful input about the diagnosis or possible treatment.