Effects of hormone replacement therapy

Author: Elapids. Reviewed and edited by Moonbeam and Nix.

Hormone Replacement therapy (HRT) is the process of modifying the bodies levels of estrogen and testosterone to induce a variety of changes to help treat and alleviate gender dysphoria in transgender individuals. Although cisgender women and cisgender men utilize hormone treatments for a variety of conditions, this article hopes to delve into the details of what changes occur when an Assigned Male at Birth (AMAB) individual brings their hormone levels in line with cisgender women, or an Assigned Female at Birth (AFAB) individual brings their hormone levels in line with cisgender men. These changes can broadly be categorized as mental changes, genital or sexual changes, secondary sexual changes, and other physical changes. These plus the risks inherent to this treatment process will be discussed below.

Towards the end of this page, we provide a bulleted list for more structured presentation of the same information.

Transfeminine HRT regimen

Undergoing feminizing HRT is most commonly done by individuals assigned male at birth and others who have naturally high levels of testosterone, especially compared to what is considered normal. The effects listed below assume a fairly typical regimen of synthetic estrogen (estradiol) and commonly an anti-androgen, such as spironolactone, finasteride, and/or cyproterone.

Mental effects

Emotional changes – 0-6 months [4]

  • Many transfeminine individuals report “feeling more feelings” and finding crying to come easier. [4]
  • Anger and irritability levels become reduced.
  • HRT is effectively inducing a second puberty and can be expected to produce the roller coaster of emotions that puberty induces on young teens. [4]

Libido changes – 0-3 months

  • Libido changes are commonly observed as a reduction or increase in sex drive. [1]
  • Changes begin almost immediately, but may not stay consistent over the course of the transition. [1]
  • Intensity and specifics of libido changes may vary depending on which anti-androgen is taken. [1]

Non HRT-induced changes

Perspectives, interests, attitudes, and other aspects of one’s personality are subject to change. This is primarily a side effect of transitioning (living as a new gender, being a minority, newly found freedom to be oneself, possible alleviation of dysphoria and depression) and not necessarily an effect of HRT in a vacuum.

Primary sexual characteristics changes

Erection changes – 0-6 months [2]

Transfeminine individuals will notice that the frequency, duration, and stiffness of erections have all decreased.[2]

Sterility – 3 months +

  • After 3 months of continuous HRT permanent loss of fertility should be assumed.[4]
  • If children are desired, prior banking of sperm will be necessary prior to beginning HRT.[2]

Orgasm changes

  • Transfeminine individuals may notice that the sensations of sexual acts are now different, with many reporting a more full body feeling for orgasms.[4]
  • Ejaculate will become more transparent, and less copious, with some individuals producing none at all.[4]

Changes to genital structure

  • Testicles will atrophy down to as little as half of their original size.[2]
  • The penis may atrophy and shrink if it is not properly utilized.
  • Skin and smell changes discussed in “Other physical changes” section will also occur to the skin of the penis and testicles.[4]

Secondary sex characteristics changes

Breast growth – 3-6 months +

  • Small breast buds begin to form behind the nipples at 3-6 months.[1]
  • These breast buds can be painful and sore while they continue to grow to their eventual size.[4]
  • Growth may stop and restart, and may continue years beyond the beginning of HRT.

Body fat distribution changes – 3 months +

  • The fat stores within the body will become relocated from their usual masculine location to a new feminine one.[1]
  • Areas affected include hips, buttocks, belly, and face.[3]
  • Body fat redistribution can have a wide range of outcomes depending on the transitioner’s age, body shape and type, bone structure, and other factors.

Changes to hair – 6-12 months

  • Body and facial hair growth can be expected to lessen and thin 6-12 months after beginning feminizing HRT.[1]
  • Electrolysis or laser hair removal are typically necessary to stop facial hair growth entirely.
  • Hair loss for the scalp (male pattern baldness) will halt or even reverse after 1-3 months.[1]

Other physical changes

Skin – 0-3 months

  • The texture of the skin changes to be softer, thinner, and drier, and is commonly among the first changes noticed after starting HRT. Skin changes may occur as quickly as the first few weeks of treatment.[1]
  • Changes to oils of the skin result in imperceptible to slightly perceptible differences in natural body odor.[4]

Muscle mass

Blocking testosterone will result in muscle mass reduction.[4]

Bone structure

  • Many transfeminine individuals report their feet shrinking one to two sizes, and losing up to an inch of height.[6,7]
  • Younger transitioners may experience a widening of the hip bones in conjunction with body fat redistribution.[4]

Voice

  • Testosterone induced voice deepening halts with the beginning of HRT or puberty blockers.[2]
  • Existing changes to the voice caused by testosterone are not undone by HRT.[1]

Period

  • Some transfeminine individuals report feeling the side effects of menstruation (bloating cramping, emotional changes) on a cycle similar to cis women.[5]

Potential health risks

Clotting

A person’s risk of strokes, heart attacks, and blood clots all increase slightly with HRT.[2]

Cancer

  • Risk of breast cancer is increased, but will remain lower than that of a cis woman.[4]
  • Regular checks for breast cancer and prostate cancer should be done on a schedule consistent with cis women and cis men respectively depending on age and risk factors.[4]

Other risks that may occur when undertaking a transfeminine HRT regimen include:

  • High triglycerides.[1]
  • High potassium.[2]
  • Hyperprolactinemia, rarely.[1]
  • Weight gain.[1]
  • If any of these risk factors are present, there will also be a heightened risk of cardiovascular disease. 

Transmasculine HRT regimen

Undergoing masculinizing HRT is most commonly done by individuals assigned female at birth and other individuals who have naturally low levels of testosterone, especially compared to what is considered normal. The effects listed below assume a fairly typical regimen of testosterone. Anti-estrogens may also be prescribed, however the expected outcomes of the HRT regimen would be the same regardless of their inclusion.

Mental effects

Emotional changes – 0-6 months

  • Many transmasculine individuals report having a reduced range of emotional experiences.
  • Anger and irritability levels become increased.
  • HRT is effectively inducing puberty and can be expected to produce the roller coaster of emotions that puberty induces on young teens.[9]

Libido changes – 0-3 months

  • Libido changes vary individual to individual, are commonly observed as an increase in sex drive.[9,12]
  • Intensity and specifics of libido changes may vary depending on which anti-estrogen is taken.

Non HRT-induced changes

Perspectives, interests, attitudes, and other aspects of one’s personality are subject to change. This is primarily a side effect of transitioning (living as a new gender, being a minority, newly found freedom to be oneself, possible alleviation of dysphoria and depression) and not necessarily an effect of HRT in a vacuum.

Primary sexual characteristics changes

Erection changes – 3-12 months

Transmasculine individuals can expect the clitoris to become larger. The enlarged clitoris functions similarly to a penis, becoming enlarged when aroused.[11]

Fertility

  • Individuals taking testosterone should not assume their fertility will remain or go away.[10]
  • If children are desired before transition, external fertility preservation methods such as freezing eggs, or freezing embryos should be explored.[10]
  • HRT may make you infertile, if you decide later you desire children, it may no longer be possible, or it may be possible only through technological fertility assistance.[10]
  • Since infertility is not assured, transmasculine individuals should still utilize estrogen-free contraceptives.[10]

Orgasm changes

Transitioners typically report that peak orgasm intensity in the genital region is greatly increased, but the intensity is significantly more concentrated to the genital region.

Changes to genital structure

  • Reduction in estrogen can cause the vagina to fail to produce lubrication to the front opening region, which can cause the vagina to become atrophied. Individuals experiencing vaginal atrophy often report feelings of dryness, burning, or itching. Small tears can form in the vaginal lining. This can begin as soon as 2 months after beginning HRT and is also experienced by post menopausal cis women.[11]
  • The clitoris begins to grow and can reach lengths of 1-3 inches. Clitoral growth starts about 2-6 months in and is typically finished after 1-3 years of treatment.[11]

Secondary sexual characteristics changes

Chest area – 6-12 months

  • If puberty blockers or cross sex hormones are used prior to chest development, further breast tissue development can be avoided entirely. 
  • After 6-12 months of masculinizing HRT, breast tissue will atrophy.[8]
  • Complete breast tissue atrophy is not likely through HRT and surgical options are typically required. These options should not be pursued within the first 6-12 months of HRT to allow time for the chest underneath to develop fully.[9]

Hair – 3-6 months +

  • Facial hair growth can begin as early as months 3-6 and continue up until 3-5 years.[10] Results can end up as diverse as for cis men.[9]
  • Changes to growth in facial hair are for the most part irreversible.[8]
  • Body hair becomes thicker, grows faster, and grows in more spots–including the chest, back, and arms.[9]
  • It is possible transmasculine individuals will develop male pattern hair loss.[9] Treatment is the same as it is for cis men. 

Body fat redistribution – 3-6 months +

  • The fat located directly underneath the skin becomes slightly thinner.[9]
  • Fat lessens around the hips and thighs, and increases around the abdomen.[9]
  • Muscle definition and vein prominence around the arms and legs will increase.[9]
  • Fat around the face will redistribute itself towards a more masculine appearance.[9]
  • Changes to body fat redistribution on masculinizing HRT will begin occurring within 3-6 months, and can continue as much as 2-5 years later.[10]

Other changes

Menstrual cycle – 2-6 months

  • After 2-6 months on testosterone, periods can become lighter, arrive later, become shorter in duration, or cease entirely.[8,9]
  • Progesterone may be used to stop periods if they do not cease on their own.[10]

Voice changes – 3-12 months + [8]

  • Vocal chords thicken to produce a deeper and more masculine-sounding voice. Experience is similar to cis men going through puberty; for example, voice cracks are to be expected.[9]
  • Voice deepening begins 3-12 months after starting HRT, usually maximum effects are experienced by 1-2 years.[8]
  • Effect is not reversible should care cease.[9]

Muscle mass – 6-12 months +

  • Muscle mass begins increasing around 6-12 months, with maximum effect experienced around 2-5 years.[8]
  • An individual’s muscle mass increases vary depending on diet, exercise, genetics, and lifestyle.[9]
  • Physical strength increases along with muscle mass.[9]

Skin changes – 1-6 months [8]

  • Fat located directly under the skin becomes thinner.[9]
  • The skin itself becomes thicker and more oily, and may experience an increase in acne.[9]

Odor changes

  • Smell of sweat and urine may change.[9]
  • Sweating should be expected to increase.[9]

Potential health risks

Cancer

  • There is currently no conclusive evidence of increased risks of breast cancer, cervical cancer, ovarian cancer, or uterine cancer.[8]
  • Transmasculine individuals do experience an increased risk of polycythemia (blood cancer). (see “blood” below)

Blood

  • Transmasculine individuals may have an increased risk of polycythemia caused by a high hematocrit count (having a surplus of red blood cells).[10]
  • Taking masculinizing HRT can lead to abnormal levels of cholesterol and other lipids.[10]
  • Masculinizing HRT can be associated with high blood pressure and deep vein thrombosis.[10]

Other risks that may occur when undertaking a transmasculine HRT regimen include:

  • Sleep apnea.[8]
  • Type II diabetes.[8]
  • Decreased bone density.[10]
  • Weight gain.[8]
  • Acne.[8]