I have been on 37.5mg of phentermine since thursday. i hurt my back earlier and want to know if it's safe for me to take 100 mg of tramadol.

Avoid the combo: Phentermine interacts with tramadol to lower seizure threshold. In other words you can have seizures with this combination. Ibuprofen (motrin, advil) or naproxen (aleve) is safe to take with phentermine.

Pharmacist: I believe that there would be no significant interaction or adverse effects of taking both medications at the same time, but your pharmacist is better qualified to answer that question as he/she has access to much more information on medications.