Quick Answer
Testosterone therapy can help men with confirmed low testosterone, but it can also cause side effects. Common ones include acne, fluid retention, breast tenderness and a rise in red blood cell count. Testosterone can also raise blood pressure and lower sperm production. A large trial called TRAVERSE found no increase in heart attacks or strokes compared with placebo, which led the FDA to update testosterone labels, but regular follow-up is still important.
Who this is for: men considering or already using testosterone therapy who want to know which side effects to watch for
Common Side Effects
Many side effects are mild and may improve when the dose is adjusted. Reported effects include:[1]
- Acne or oily skin
- Mild fluid retention, such as ankle swelling
- Breast tenderness or enlargement
- Smaller testicles
- Skin irritation where a gel or patch is applied
- Worsening of sleep apnea
Let your provider know if you notice any of these. Snoring that gets louder or daytime sleepiness can be signs that sleep apnea is getting worse.
Blood, Fertility and Prostate Effects
Testosterone can increase the number of red blood cells, which thickens the blood. This is called erythrocytosis, and it is one of the main reasons lab checks are part of treatment.[1] Our article on testosterone therapy lab monitoring explains what is checked and how often.
Testosterone therapy also lowers the body’s own sperm production and can reduce fertility. If you may want children in the future, read Can Testosterone Therapy Affect Fertility? and raise it before starting.
Testosterone can raise PSA levels and may cause urinary symptoms from prostate growth.[1] In June 2026, the FDA asked makers to update prostate-related label language based on newer data, including limiting the prostate cancer contraindication to metastatic disease. These were requested updates, and screening and monitoring are still recommended.[2]
Staying active and getting regular checkups are part of using testosterone therapy safely.
What We Know About Heart Safety
For years, testosterone labels carried a boxed warning about possible heart risks. The TRAVERSE trial was designed to answer that question. It followed more than 5,000 men aged 45 to 80 with low testosterone who already had heart disease or several heart risk factors. Major heart events, such as heart attack, stroke and heart-related death, occurred in 7.0% of men using testosterone gel and 7.3% of men on placebo.[3]
Based on these results, the FDA announced in February 2025 that heart-risk language would be removed from the boxed warning on testosterone products.[4] TRAVERSE did find that some other problems were more common with testosterone, including atrial fibrillation (an irregular heart rhythm), acute kidney injury and blood clots in the lungs.[3] These events were uncommon, but they are worth knowing about.
Blood Pressure
As part of the 2025 update, the FDA added warnings that testosterone can raise blood pressure. Blood pressure studies found an increase with testosterone products across the class.[4] Over time, higher blood pressure can raise heart risk.
Checking blood pressure before and during treatment is a simple way to catch changes early. Some labels advise against use in people whose high blood pressure is not controlled.[3]
Other Safety Cautions
Testosterone gels can pass to a partner or child through skin contact while the gel is still wet.[1] Covering the area and washing hands helps lower this risk.
Testosterone therapy is generally not recommended for people with untreated prostate or male breast cancer, untreated heart failure, untreated severe sleep apnea, a recent heart attack or stroke, or a history of high red blood cell counts.[1] Sharing your full health history helps your provider decide whether treatment is a safe fit.
Most risks can be managed with a careful start and regular check-ins, so reporting changes early matters.
How We Approach Testosterone Therapy Safety at Lake Forest Regenesis
Before recommending testosterone therapy, Allana reviews your symptoms, labs, heart health, sleep, prostate history and family plans. If therapy is a good fit, she talks through the possible side effects, the options for how testosterone is given and what follow-up will look like. Ongoing visits and labs help her watch for changes in blood counts, blood pressure and how you feel, and adjust care as needed.
When to See a Provider
Call 911 for chest pain, shortness of breath, sudden weakness or numbness, face drooping or trouble speaking. Seek urgent care for pain, swelling or warmth in one leg, which can be signs of a blood clot. Contact your provider if you notice a racing or irregular heartbeat, new snoring or daytime sleepiness, trouble urinating, breast changes or swelling in your ankles.
Related Service
Thinking about testosterone therapy or noticing side effects? Allana can review your symptoms, labs and health history to help you decide what is safe for you.
Frequently Asked Questions
Does testosterone therapy cause heart attacks?
The large TRAVERSE trial did not find an increase in heart attacks or strokes in men with low testosterone and heart risk factors. Blood pressure and heart rhythm still need watching.
Will side effects go away if I stop?
Many side effects, such as acne or fluid retention, often improve after the dose is lowered or treatment stops. Fertility may take months to recover and does not always fully return.
Can testosterone therapy cause prostate cancer?
Current research has not shown that testosterone causes prostate cancer, but it can raise PSA. Screening before treatment and monitoring during treatment are still recommended.
Are side effects different between gels, injections and other forms?
Some are. Gels carry a risk of passing to others and can irritate skin, while injections may cause swings in how you feel between doses. Blood pressure and red blood cell effects can happen with any form.
References
- Cleveland Clinic. Testosterone replacement therapy (TRT): what it is. Read the article
- U.S. Department of Health and Human Services. HHS announces requested updates to testosterone therapy product labels. Read the article
- U.S. Food and Drug Administration. AndroGel prescribing information, including TRAVERSE trial results (2025). Read the guidance
- U.S. Food and Drug Administration. FDA issues class-wide labeling changes for testosterone products. Read the guidance
This article is for general education and is not a substitute for individual medical advice. See our medical disclaimer.
