Note that in this article biological terms will be discussed.

Testosterone treatment is designated for people on the trans spectrum who are interested in hormone replacement therapy (HRT) in the masculinization direction.
The treatment is given by taking the testosterone hormone. כיוון שהטסטוסטרון הוא הורמון דומיננטי, אין צורך לקחת חוסמים בנוסף לטסטוסטרון, זאת בניגוד לנטילת הורמונים לנישוי.

Testosterone is the sex hormone generated in the testicles in most people assigned as male at birth, and in the ovaries in most people assigned as female at birth (in those who were assigned as female at birth it breaks down into other hormones and usually exists in the body in smaller quantities).

This article will detail the physical, emotional, and sexual effects of testosterone HRT, as well as the side effects and risks that are important to be aware of.
Note that there is no way to estimate how the body will react to HRT. The reaction changes from person to person and is inherently affected by variations in genetics, age, health condition, and more. Therefore, it is important to evaluate your expectations with yourself and with your doctor.

In Israel, testosterone is available as an injection into fat or muscle at different doses (which you can do at home or through nurse services) or as a gel. Here as well it is important to consult with your doctor to determine which method is most suitable for you. Some people report different absorption with gel and injections. You may need to do some trial and error to figure out what is best for your body.

Physical Changes

There are several expected physical changes during testosterone treatment. Not all changes happen to every person who begins testosterone HRT, and each change can begin at different stages for different people. חלק מהשינויים מושפעים ממינון הטסטוסטרון הנצרך.
In most cases, you can expect the following changes:

• 1-3 months after starting treatment – menstruation stopping, clitoris growth, voice deepening.
• 3 months to one year – continuation of the previously mentioned changes, as well as redistribution of body fat, facial hair and body hair growth, muscle mass and strength increase, hairline changes. Facial and body acne is also possible. Another potential effect is changes in chest structure as part of body fat redistribution, as well as facial structure changes. Some people also experience growth of the legs, arms, and nose and may even gain a few centimeters in height, due to changes in soft tissue and ligaments (not the bones).
• 1 year onwards – signs of balding (depending on genetics and family predisposition for male-pattern baldness).

The changes can parallel a “second puberty” (for those who begin treatment after the age of puberty) and can look different depending on the person. There are some who will grow a beard within several months while their voice remains high, while others may take 5-10 years to grow facial hair but their voice deepens significantly within two months.
Some effects are reversible after stopping HRT, while others are less reversible or are permanent.

Sexuality and Fertility

Usually, testosterone treatment will cause an increase in libido. The initial period is defined by significant changes, the clitoris/penis itself increases in size, especially during the first few months of HRT.
The growth can sometimes be accompanied by pain or hypersensitivity, and most people report different sexual sensations, more evident erections, and different usage of different parts of the sex organ. With time, atrophic dryness of the vaginal tissues can develop and cause pain, so it is best to use lubrication products during penetration, as well as consultation with your doctor about treatments such as localized estrogen creams.

Testosterone treatment lowers the chances of pregnancy but does not eliminate the possibility entirely, so it cannot be used as a replacement for contraception. Research on the subject is limited, but the information available today indicates that even after many years of hormones, it is possible to stop taking testosterone and become pregnant or to produce fertile eggs. However, this can depend on fertility status before HRT and there is risk involved. You can consider egg-freezing options before beginning treatment (and sometimes during treatment, but it is necessary to pause treatment to begin the egg-freezing process).

For expansion about fertility preservation

Emotional Effects

The effects of HRT can vary widely from person to person. However, there are several emotional changes that it is important to be aware of. Starting HRT is similar to puberty, which can be accompanied by mood swings and intense emotions.
Usually, people report feeling more anger, improvements or changes in existing mental conditions (anxiety, depression, ADHD), or experiences of more unclear or narrow ranges of emotion and difficulty crying.
לאחר התייצבות הטיפול ישנה לרוב התייצבות בתנודות.
In cases where there is concern about mood swings, it is recommended to consult with your doctor or with your support network before beginning treatment and to discuss managing expectations about the expected changes.
Additionally, hormonal treatment can change the relationship between mind and body, and an adaptation and adjustment process may be necessary. It is recommended to follow up with a doctor and to utilize therapy, a support network, nutrition, exercise, or any other support that you may need. It is important to know that it is possible to change the dose and frequency of hormones, and it is highly recommended to consult with your doctor.

Risks and Side Effects

Testosterone HRT may “raise the risk” – that is, to equate the risk to that of people assigned male at birth, of diseases such as heart disease, high blood pressure, and high cholesterol. However, it is important to know that research that directly investigated the risk of trans men for conditions such as heart disease, attributed it to the social pressure and discrimination that people on the trans spectrum experience, and not directly to the hormonal treatment.
Additionally, certain studies show negative effects on the liver from long-term exposure to synthetic hormones. It is recommended to consult with your doctor and receive monitoring to protect your health throughout treatment.

Testosterone treatment should stop menstruation, but there is a chance that bleeding does not stop and/or menstruation returns at some point. Consult with a doctor to change the dose or amount of time between doses to tailor treatment to your body.

There may also be side effects such as acne, body hair, baldness, weight gain, snoring, or hot flashes, which can be affected by genetics. Some people discover during treatment that they cannot continue taking testosterone due to health risks or choose not to take testosterone to not experience certain effects. Choosing HRT is an individual choice and does not indicate anything about your identity. Some trans people choose to transition with hormones and some choose not to. Some start and then stop later. It is a choice that depends on a wide range of mental, environmental, and health factors.