How long does it take for effects of testosterone replacement therapy for hypogonadism?

Depends!: Time for effects of testosterone replacement to be noticeable depend upon route/dose, effect & you! most branded t can make subjective improvements in mood, thinking, sex drive (libido) & erectile function in days if given in an adequate dose. But increase in muscle & loss of fat will only occur if you eat right & exercise in add'n to taking t. If you take too much t, conversion into e2 will rob u.

Usually after 3-4th: Cycle but full effect can only be expected if serum testosterone levels are checked and are in the mid to upper third centile.