The female to male (FTM) person will usually seek hormonal treatment as the first step towards their new body. In order to get testosterone for the FRM, which is the masculanising hormonal therapy, it is necessary to have a prescription.
It is possible to get these hormones illegally, but it is not advised, and can cause severe damage. An endocrinologist writes the prescription, and monitors how your organs are coping with the testosterone once treatment has begun.
Some of the changes from testosterone are permanent and irreversible, while others are maintained only through continuous use.
Each person who takes testosterone reacts to it and experiences it differently on an emotional level. You will not know how you will react to the treatment until you start it yourself.
Physically, the changes that occur are generally the same for everyone. However, it is important to be realistic about your body, and expect the changes to be in proportion to how your body looks at the start. If you are short and skinny, chances are that you will not look like a WWF wrestler at the end of it.
The permanent changes include a deepening of your voice; increased body hair on your thighs, abdomen, back, arms and chest; facial hair; receding hairline and possible baldness; Adams apple and facial bone thickening; enlargement of clitoris; and your skin becomes coarse.
The changes that are not permanent, and which will go away if you should stop taking testosterone include decrease of fat in buttocks, breasts and thighs, and an increase in fat on abdomen; an increase in red blood cells; increase in ability to grow muscle; increase in sex drive; weight gain; and menstruation ceases.
Testosterone will not grow you a penis or make your breasts disappear. The changes that do occur are slow, and depending on your dose, will take from a few months to up to five years to complete. Testosterone is not a birth control measure, and you can fall pregnant if your female genitals come into contact with sperm.
Risks associated with testosterone use include liver damage; increased risk for breast cancer, even after top-surgery; increased risk for uterine cancer. - (Health24)