Any over the counter “T” booster they sell or rep would have to be by pill (oral pill). Testosterone is a hormone— therefore is a protein by definition. Protein goes in the stomach (pH 2 very acid digestion in stomach) which denatures, breaks down the hormone into... components. So, any OTC med that is whole hormone... is a waste of money.
Prescription is required for transdermal Testosterone- by a physician, not a quack.
There is a helpful prodrug which is metabolized into Testosterone naturally (this is NOT an anabolic steroid to build muscle mass like weightlifters use, to their coronary and testicle size deficit).
Over the counter as DHEA Dihydro Epaniandrosterone— discussed all over MedMD and other sites. Again- not a dangerous anabolic steroid, which will lower good HDL cholesterol and bad for cardiac risk.
My two cents. DHEA does work to maintain muscle strength, with proper diet and proper dosing. All anabolic steroids of any effect- if sold or provided by one of these clinics— they are violating federal pharma law. If there’s a “doctor” there he better be licensed and also have a clinical diagnosis to inject someone.
Everybody gets older- and genetics plays the biggest part in how quickly and.... how. There is no such thing as “Ageless Male” or “Stud Muffin” or “Get Hard” and all the other huckster crap sold on radio or these “men’s “ sort of quack clinics. So watch out. They are into... your money.
DHEA does not convert primarily to testosterone in males, but remarkably well in females.
Any increase in testosterone by DHEA will also aromatize to estrogen in most cases- this is where dosage plays a huge part as you mentioned.