Hey Kaden. I'm not sure if your friend is taking oral testosterone or dietary supplements that are marketed as testosterone boosters. Either way, it is advised to consult with a health care provider before beginning any new drug, herbal preparation, or dietary supplement. New medications, including supplements and hormones, can interfere with current medications and body chemistry (including cholesterol levels, blood pressure and heart rate, potassium and calcium levels, and various other side effects depending on the drug).
OTC supplements are not regulated by the FDA the same way that drugs like testosterone are. "Conventional" drugs are rigorously tested with clinical trials that can last for many years. Dietary supplements, including "T-boosters" like DHEA and creatinine, are not required to go through those clinical trials and the manufacturers only have to prove that the product label is truthful and not misleading (advertising can give a lot of leeway here though). The FDA just assures that the product is safe for human consumption, not the the supplement actually works or does what the manufacturer says it does.
I would stress the importance of going through the proper channels and taking all medications safely. Let your friend know that you're concerned about his health and that you support him in his transition, just not taking pills that could be dangerous for his health. If you could find out the name of the medication he is taking, I could try to get you more specific information. I'm in school to become an RN and have some resources.
