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A pill bottle with an exclamation mark on the label: Testosterone side effects
Drug Info

Testosterone side effects and how to avoid them

Testosterone side effects include acne, ankle swelling, disturbed breathing while sleeping, and breast tenderness, among others
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By | Dec. 26, 2023 Medically reviewed by Chad Shaffer, MD

Key takeaways

  • Testosterone therapy can lead to both common and serious side effects, including acne, ankle swelling, disturbed breathing while sleeping, breast tenderness, increased risk of heart attack, and stroke.

  • The onset of testosterone side effects varies, with some appearing immediately after treatment begins, while others, such as heart and liver issues, may develop over time with prolonged therapy.

  • Testosterone has specific interactions with other drugs, including those used for prostate cancer and blood thinners, requiring careful management and sometimes dosage adjustments.

  • To minimize side effects, patients should share their full medical history and current medications with their prescriber, closely monitor for adverse effects, and be prepared to adjust or discontinue therapy if necessary.

In this article:

Testosterone is the male sex hormone or androgen responsible for male characteristics, sexual organ function, and sperm production. As a prescription drug, testosterone is used as testosterone replacement therapy (TRT) for men who have low testosterone levels (low T) or symptoms of hypogonadism. It’s also used to treat teen males with delayed puberty. Some healthcare providers may prescribe it off-label for erectile dysfunction or to women for certain conditions. 

A variety of testosterone products are available. Intramuscular injections and transdermal gels are among the most common, but other forms include subcutaneous injection, oral capsules, topical gels, topical solutions, implanted pellets, and nasal gel. These various forms may have unique side effects, but they all share a number of common side effects.

Common side effects of testosterone

Side effects of testosterone depend upon the form taken, but the most common side effects are acne, ankle swelling, disturbed breathing while sleeping, and breast tenderness or swelling. 

Each formulation has commonly experienced side effects unique to the way it’s taken:

Serious side effects of testosterone

Testosterone hormone therapy has several serious side effects. The most common severe adverse effect is an increase in red blood cells called polycythemia or erythrocytosis. The estimated incidence is between 1% and 14%.

Other serious side effects of testosterone include:

  • Electrolyte abnormalities
  • High blood pressure
  • Blood clots
  • Bleeding
  • Prostate enlargement
  • Increased risk of prostate cancer
  • Increased risk of heart attack
  • Increased risk of stroke
  • Increased risk of liver cancer (rare)
  • Priapism (persistent and painful erections)
  • Liver problems
  • Severe allergic reactions
  • Abuse
  • Dependence

How soon do testosterone side effects start?

Many testosterone side effects can begin immediately, particularly reactions to an injection, gel, or nasal gel. Allergic reactions can also happen shortly after application.

Most of the common side effects start early in treatment, including elevated blood pressure, nausea, and mood swings. Other side effects are delayed, such as breast growth, weight gain, irritability, blood changes, prostate problems, and many of the severe side effects, such as heart attack, stroke, or polycythemia. People will require regular monitoring and blood tests throughout therapy.

How long do testosterone side effects last?

Side effects such as administration reactions, headaches, and nausea may improve as the body gets accustomed to the drug. Other side effects, such as mood changes and acne, may last as long as testosterone therapy lasts. Breast growth, unwanted hair growth, prostate problems, and blood changes may also be long-term effects that may worsen as therapy continues. 

What are the long-term side effects of testosterone?

Testosterone therapy has some side effects that are due to long-term use, including breast development (gynecomastia), weight gain, and prostate enlargement. The worsening of existing conditions like sleep apnea is also a longer-term side effect. Many of the most hazardous side effects of testosterone, such as heart attack, stroke, and cancer, become more likely the longer therapy lasts. Some side effects may be permanent. For instance, testosterone causes women to develop male characteristics such as a low voice or facial hair, a condition called virilization, which may become permanent in cases of long-term testosterone treatment. 

Testosterone interactions

Testosterone has relatively few drug interactions, but there are three types of drug interactions that healthcare providers are concerned about:

  • Although the combination isn’t dangerous, healthcare providers do not use testosterone injections in people taking drugs designed to decrease testosterone levels, such as the prostate cancer drugs histrelin or leuprolide. These drugs have the opposite effect of testosterone, so they will cancel each other out. 
  • Testosterone increases the ability of warfarin, a member of the vitamin K antagonist class of anticoagulants, to thin the blood—thereby increasing the risk of bleeding problems. The combination may require close monitoring and dosage adjustments.
  • Testosterone injections may decrease blood glucose levels, so people taking insulin or diabetes medications may require dosage adjustments.

Safety measures while using testosterone

What are the FDA warnings about testosterone?

The Food and Drug Administration (FDA) has multiple boxed warnings for testosterone therapy. Warnings on testosterone undecanoate mention the risk of pulmonary oil micro-embolism with intramuscular injection and blood pressure elevation with the oral form. Similarly, subcutaneous testosterone enanthate carries a warning about raising blood pressure, too. Transdermal testosterone gels and solutions have warnings about the virilization of children who are exposed to the product by touching the application site of the individual. In addition, the FDA has cautioned against the use of testosterone in older men to treat age-related testosterone decline because of the risk of severe side effects.

Who should never take testosterone?

People with any of the following medical conditions should avoid taking testosterone:

  • Allergies to any substance in the drug
  • Pregnancy
  • Breast cancer 
  • Prostate cancer
  • Serious heart disease
  • Severe liver disease
  • Severe kidney disease
  • Polycythemia (high red blood cell count)

Who should use caution with testosterone?

Because of its numerous side effects and risks, testosterone is used cautiously in several types of patients with certain conditions:

  • Mild or moderate cardiovascular disease
  • Mild or moderate kidney disease
  • Mild or moderate liver disease
  • Risk factors for prostate cancer
  • High blood pressure
  • High cholesterol
  • Diabetes
  • Excess weight
  • Obstructive sleep apnea
  • Enlarged prostate

Older men should also practice caution when considering testosterone therapy and speak with their healthcare provider about potential side effects. Adolescent teens taking testosterone for delayed puberty are at risk of bone growth issues, so prescribers may monitor bone development during therapy.

Women are at risk of developing male characteristics such as facial hair, deep voice, and menstrual changes. Healthcare professionals will monitor for these changes and discontinue testosterone treatment if they occur.

Does testosterone cause drug abuse or dependency?

The FDA has classified testosterone drugs as Schedule III controlled substances because of their potential for abuse and dependency. Some people abuse testosterone and other anabolic steroids to increase muscle mass, raise energy levels, and improve athletic or bodybuilding performance. Nontherapeutic use of testosterone is dangerous and can cause severe side effects, including heart failure, heart attack, stroke, and severe psychiatric disorders.

Can you overdose on testosterone?

An overdose is unlikely because testosterone is either administered by a healthcare provider or used in slow-release formats. However, overdose is possible, especially if it’s being abused. Persistent overdoses over time can lead to severe side effects, but there isn’t much information about a one-time overdose. If too much testosterone is taken, call at 800-222-1222 for medical advice or get medical treatment.

Is testosterone safe to take when pregnant?

No. Testosterone is contraindicated in pregnant women because it can harm the fetus or cause congenital disabilities.

Is testosterone safe to take while breastfeeding?

Testosterone can affect milk production. High levels of testosterone may suppress lactation, and testosterone can be detected in breast milk, leading some to recommend avoiding testosterone therapy while breastfeeding. 

Is testosterone safe for children?

Testosterone is not FDA-approved for use in children younger than 12 years old. Boys 12 years and older can be prescribed testosterone for delayed puberty. Testosterone affects the bones, so healthcare providers will monitor bone development during therapy. 

Is testosterone safe for seniors?

Testosterone can be prescribed for people older than 65, but the FDA has cautioned that it shouldn’t be used for testosterone deficiency due to aging because of the increased risk of heart attack, stroke, and prostate cancer. 

How to avoid testosterone side effects

Testosterone side effects are commonly experienced, and some people are at risk for serious side effects. There are ways to minimize the possibility of side effects:

1. Tell your prescriber about all medical conditions.

People are more likely to experience severe side effects if they have certain types of common medical conditions, so your prescriber needs to know about other conditions you might have, particularly:

  • Breast cancer
  • Prostate cancer
  • Heart problems
  • Coronary artery disease
  • Liver problems
  • Kidney problems
  • History of blood clotting problems
  • Urination problems 
  • Sleep apnea
  • High blood pressure
  • High cholesterol or triglycerides
  • Diabetes
  • High red blood cell counts

2. Tell your doctor about all medications you’re taking.

Make sure your prescriber knows about all prescription drugs, OTC medications, and dietary supplements you’re taking. In particular, your prescribing healthcare provider needs to know about insulin, diabetes medications, and blood thinners.

3. Ask your doctor about side effects unique to the format prescribed.

Each type of testosterone product can have different side effects, so ask your prescriber about the specific side effects, how to protect yourself from them, and what to do if you experience them.

4. Inform your prescriber about all adverse effects.

Even if a side effect or change seems minor, tell your prescribing healthcare provider about it. Minor physical or psychological complaints may be a sign of a more serious problem caused by testosterone therapy. For instance, high red blood cell counts are a potentially serious side effect of testosterone because it increases the risk of blood clots. You can’t see high red blood cell counts. But you may get headaches, blurred vision, nosebleeds, fatigue, more bruises on the skin, or shortness of breath. Your prescriber needs to know about these side effects.

5. Do not take anabolic steroids along with testosterone.

Anabolic steroids taken to increase muscle mass or improve athletic performance have the same effects as testosterone. Combining them with testosterone therapy will increase the risk of potentially hazardous adverse effects.

How to treat side effects of testosterone

Testosterone side effects are common, but most are bearable. Some side effects, however, will require medical attention, including:

  • Any sign of heart problems, such as chest pain, heartbeat irregularities, and shortness of breath
  • Any sign of liver problems, such as fatigue, bruising, bleeding, weakness, or yellowing of the skin or eyes
  • Any sign of prostate problems, such as decreased urination, difficulty urinating, painful urination, or frequent urination
  • Any sign of high red blood cell counts, such as bruising, nosebleeds, dizziness, or shortness of breath
  • Symptoms of a blood clot, such as leg pain, difficulty breathing, or sudden weakness or numbness on one side of the body
  • Any worsening of sleep apnea
  • Symptoms of anxiety, depression, mania, paranoia, and other psychiatric disorders
  • In women, the development of male sexual characteristics such as deep voice, facial hair, male-pattern baldness, or enlargement of the clitoris

Bottom line: Is testosterone safe?

Testosterone replacement therapy has benefits and potential risks. Because of the benefits, the balance between benefits and risks makes it a reasonable drug to take for low testosterone, hypogonadism, and delayed puberty. However, it can cause many serious side effects, particularly in people with certain risk factors. Patients should get medical advice from a healthcare professional about balancing benefits and risks. Upon starting testosterone therapy, it’s important to watch vigilantly for side effects or symptoms of severe side effects. Finally, people should be ready and willing to discontinue testosterone therapy if side effects warrant it.

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