Testosterone Replacement Therapy for Men and Women

Testosterone is one of the most talked-about hormones in medicine. It is also one of the most misunderstood. In the United States, the number of testosterone prescriptions more than tripled between 2001 and 2013. Most of that growth came from men who wanted help with tiredness, low sex drive, and the normal changes of getting older, not from men who had a real disease (Walker et al., JAMA Internal Medicine, 2020). At the same time, more and more women are being offered testosterone for a growing list of problems.

It matters to know the difference between real treatment and wishful thinking. Testosterone is a strong drug. It can truly help the right patient. It can truly harm the wrong one.

This post explains who really benefits, how the drug is given, what side effects to expect, and what happens when people take it without meeting the rules for treatment.

When testosterone is truly needed

In men. 

There is really only one clear reason to use testosterone: to replace what the body is missing when a man has a real hormone shortage. Doctors call this pathological (organic) hypogonadism. It happens when disease damages the parts of the body that make or control testosterone, the testicles, the pituitary gland, or the hypothalamus in the brain. Causes include Klinefelter syndrome (a genetic condition), pituitary tumors, injury to the testicles, and radiation. In the U.S., the FDA only approves testosterone for men whose low levels come from problems like these (Diem et al., Annals of Internal Medicine / ACP evidence report, 2020; Handelsman, Endocrine Reviews, 2021).

Symptoms alone are not enough to make the diagnosis. The Endocrine Society and the American Urological Association say a man should have two separate blood tests showing low testosterone before he is diagnosed. Both tests should be done early in the morning, before eating (Bhasin et al., Endocrine Society Clinical Practice Guideline, 2018). The help from treatment is strongest when levels are clearly low. The lower the level (for example, under 200 ng/dL), the more benefit a man can expect. Testosterone reliably improves sex drive, but it often does not help when the main problem is trouble getting an erection (Bhasin and Snyder, New England Journal of Medicine, 2025).

In women. 

There is only one use backed by strong evidence: low sexual desire that causes distress in women who have gone through menopause. Doctors call this hypoactive sexual desire disorder, or HSDD. It should only be treated after other causes are ruled out. A large group of hormone and menopause experts reviewed the research together. They found that testosterone—given in small amounts that match the levels of a younger woman, improves desire, arousal, orgasm, and pleasure, and lowers sexual distress. On average, it adds about one more satisfying sexual event per month (Davis et al., Global Consensus Position Statement, 2019; Davis, New England Journal of Medicine, 2024).

Just as important: the research does not support giving testosterone to women for energy, mood, sense of well-being, memory and thinking, bone strength, or muscle strength. There is also not enough evidence to use it in women who have not yet gone through menopause, for any reason (Davis et al., 2019). One review of 36 high-quality studies found testosterone beat a placebo (a fake pill) only for sexual function. For everything else, the fake pill worked almost as well, which shows a strong placebo effect (Lenharo, Nature, 2026).

How testosterone is given

Testosterone comes in several forms. Each has trade-offs in cost, ease of use, and side effects.

For men, common choices include (Jayasena et al., Society for Endocrinology, 2022; Heidelbaugh and Belakovskiy, American Family Physician, 2024):

• Shots into the muscle or under the skin (testosterone enanthate or cypionate). These are usually given as 50–100 mg once a week, or 150–200 mg every two weeks. They are cheap and easy to find. But levels can spike and then drop, which causes ups and downs in how a man feels. They also carry a higher risk of making too many red blood cells.

• Gels and liquids rubbed on the skin, used once a day on clean, dry skin. Do not put them on the genitals or on skin that touches a partner or a child. They keep levels steady but can rub off onto other people.

• Skin patches, changed each night. They copy the body's natural daily rhythm but often irritate the skin.

• Long-acting shots (testosterone undecanoate), given only a few times a year, and an oral (by mouth) form of the same drug. Both carry an FDA "boxed warning"—the strongest warning the FDA gives—for raising blood pressure and for serious heart problems.

• Small pellets placed under the skin every 3 to 6 months. They keep levels steady but need a minor office procedure, and they are hard to adjust or remove.

• Tablets that dissolve in the mouth and a nasal gel. These avoid shots but must be used often.

The dose is adjusted to bring levels into the middle of the normal range (a common target in men is about 450–600 ng/dL). Doctors then check the testosterone level and the red blood cell count from time to time.

For women, only a few countries, Australia, New Zealand, South Africa, and the United Kingdom, have testosterone products made just for women. Everywhere else, doctors use it "off-label," meaning outside its approved use. Experts prefer forms rubbed on the skin, not swallowed. This means a cream made for women where it exists, or a carefully measured small part of a men's gel. Pills are not recommended because swallowed testosterone worsens cholesterol. Shots, pellets, and custom-mixed (compounded) products are discouraged. They can push levels far too high and cause harm (Davis et al., 2019; Davis, 2024). When testosterone is used, blood levels should be checked regularly to keep women in the normal range for a younger woman and to watch for signs of too much hormone.

Side effects and risks

At normal replacement doses, testosterone is usually well tolerated. But some effects are expected.

In men, the most common side effects are acne, oily skin, and tender breasts. Making too many red blood cells (called erythrocytosis) is the most common problem seen in studies, which is why the blood count must be watched (Bhasin et al., 2018). Other known risks include shrinking of the testicles, less sperm and possible infertility, breast growth, fluid buildup, worse sleep apnea, and a small drop in "good" (HDL) cholesterol (Diem et al., 2020). Recent studies link testosterone to a higher risk of blood clots in the lungs, broken bones, and possibly an irregular heartbeat (atrial fibrillation). However, a large study called TRAVERSE did not find more major heart problems, prostate cancer, or urinary problems (Bhasin and Snyder, New England Journal of Medicine, 2025). Even so, the FDA requires a warning about the possible risk of heart attack, stroke, and blood clots (Grossmann et al., Journal of Clinical Endocrinology & Metabolism, 2023).

Some men should not use testosterone. These include men with untreated severe sleep apnea, heart failure that is not under control, a heart attack or stroke in the last 6 months, a tendency to form blood clots, and untreated prostate or breast cancer (Bhasin et al., 2018).

In women, normal doses may cause mild acne and a little more body or facial hair. They do not usually cause scalp hair loss, a deeper voice, or enlargement of the clitoris (Davis et al., 2019). Those stronger, more "male" changes, along with weight gain, feeling agitated, and aggression, show up when the dose is too high. Some of these changes cannot be undone.

What happens when testosterone is used the wrong way

This is where today's testosterone boom becomes a public health worry. Most people taking testosterone do not have the disease it was made to treat.

Real testosterone shortage is much rarer than ads suggest. In a large European study of men aged 40 to 79, only about 2.1% had both low testosterone and clear symptoms of a shortage. In a set of major studies called the Testosterone Trials, researchers screened more than 51,000 men and found fewer than 1,000 who truly qualified (Gagliano-Jucá et al., Reviews in Endocrine & Metabolic Disorders, 2022). Yet the number of prescriptions is far higher than the number of men who really need it. Many men are even started on testosterone without ever having their level checked, or with a level that is actually normal. In one study, about 20% of men who started treatment had a level above 300 ng/dL before they began, which is normal (Diem et al., 2020).

Common but unproven reasons people take testosterone include:

• "Anti-aging" or feeling young again. Some treat the small, normal drop in testosterone that comes with age, often blamed for tiredness, weight gain, or low drive, as if it were a disease. There is no proof this is safe or helpful (Handelsman, Endocrine Reviews, 2021).

• Vague symptoms in men with obesity or diabetes. In these men, low-normal levels are usually caused by the weight or the disease itself. Testosterone is less likely to help. Losing weight or treating the other condition works better (Bhasin and Snyder, 2025).

• Erection problems by themselves. Testosterone often does not work when the main issue is trouble with erections rather than low sex drive (Bhasin and Snyder, 2025).

• Building muscle or improving looks. Some athletes and bodybuilders use these drugs—often at doses many times higher than any real treatment, and without a prescription—to gain muscle and change their body. This is drug abuse, not treatment, and it carries the greatest risk of harm (Handelsman, 2021).

• Women looking for more energy, better mood, or weight loss. These are exactly the results where testosterone did not beat a placebo. And high custom-mixed doses can cause male-type changes in women (Davis, 2024; Lenharo, Nature, 2026).

The harms of wrong use are real, not just theories. Taking testosterone without need, especially at high doses, shuts down the body's own hormone production. This shrinks the testicles and can cause infertility that lasts even after stopping. It thickens the blood, which raises the risk of clots. Custom-mixed and unregulated products give unpredictable doses. And stopping suddenly after high-dose use can leave a person feeling "flat and miserable" (Davis, 2024). Women given doses that are too high have reported permanent voice changes, hair loss, an enlarged clitoris, and, surprisingly, new agitation and aggression (Lenharo, 2026).

The main point

Testosterone is a real and helpful treatment, but only for a small group: men with a confirmed, disease-based hormone shortage, and women past menopause who have low sexual desire that troubles them. For everyone else, people chasing energy, youth, weight loss, an edge in sports, or a vague feeling of vitality, there is little or no proof it helps, while the risks are real. Anyone thinking about testosterone should get a proper checkup first (including repeated morning blood tests), use a regulated product at normal doses, and be watched over time. Treating a number, a single symptom, or a promise from an ad, instead of a real diagnosis, is where testosterone therapy goes wrong.

This article is for general education only. It is not a substitute for advice from your own doctor.