Can i use a testosterone booster without asking a doctor?

Only illegally: If you mean actual testosterone, that is only available legally by prescription. If you mean a supplement that helps your body make testosterone, there are several commercial supplement s of dubious benefit. Your best bet is to have a blood test and check your level.

No it is a bad idea: No it is a idea.At your age there is usually no need to boost testosterone unless you have hypogonadism and low blood testosterone level. It can cause 1acne 2enlargement of breasts 3reduction in size of testis 4sleep apnea 5problem in urination due to stimulation of prostate;elevated psa 6moodiness and aggressiveness 7increase in red blood cell level 8levels of cholesterol and lipids in some case.