Testosterone side effects: what to watch for
Testosterone side effects range from acne and swelling to serious blood clots and heart risks. Know the warning signs and when to call a clinician.
Key facts
- Answer a few health questions online. A licensed clinician reviews them. If approved, it ships to your door.
- Adults 18 or older. A licensed clinician reviews your health history and decides whether treatment is appropriate for you. Availability depends on the state you live in.
Testosterone therapy can help some men with confirmed low testosterone, but it also has risks. The most important step is knowing which effects are common and which symptoms mean you should contact a clinician right away. This guide summarizes testosterone side effects seen across FDA labeled testosterone products and what to do next. If you are unsure whether a symptom is related, Vitals Vault can help you start with labs and share results with a clinician.
- Testosterone side effects can be mild (acne) or serious (blood clots and heart events).
- Testosterone can raise red blood cell count, which may increase clot risk.
- It can lower sperm production and may affect fertility while you are on therapy.
- Gel can transfer to others through skin contact and cause unwanted exposure.
What are the side effects of testosterone?
Common vs serious testosterone side effects
Acne and oily skin
Androgens like testosterone can increase oil production in skin, which can worsen acne. If acne is new, severe, or scarring, tell your clinician because it can signal that your level is higher than intended. Skin care changes and adjusting the plan may help.
Fluid retention and swelling
Some people notice ankle or leg swelling or weight gain from fluid retention. This can be more concerning if you have heart, kidney, or liver disease. Call your clinician promptly if swelling is new, one sided, painful, or comes with shortness of breath.
Breast tenderness or enlargement
Testosterone can be converted to estradiol (an estrogen), which may contribute to breast tenderness or gynecomastia. This is not an emergency, but it is worth discussing because it can affect comfort and may change monitoring or medication choices. Report any new breast lump.
Fertility and testicular changes
Testosterone therapy can suppress the signals from the brain that stimulate sperm production, which can lower sperm count and reduce fertility while you are on treatment. Some men also notice smaller testicular size. If fertility is a goal, discuss alternatives and timing with a clinician before starting or continuing therapy.
High red blood cell count (polycythemia)
Testosterone can raise hematocrit, meaning your blood has a higher proportion of red blood cells. Higher hematocrit can increase the risk of blood clots and related complications, so clinicians typically monitor blood counts during therapy. Seek urgent care for symptoms of a clot such as sudden chest pain, shortness of breath, coughing blood, or one leg swelling and pain.
Heart and blood vessel events
FDA labeling warns about possible increased risk of heart attack and stroke with testosterone use, especially in certain populations. Get emergency care for chest pressure, sudden weakness on one side, trouble speaking, or sudden severe headache. If you have cardiovascular disease risk factors, review them with your clinician before and during treatment.
Blood clots in veins (DVT or PE)
Testosterone products carry warnings about venous thromboembolism, including deep vein thrombosis (DVT) and pulmonary embolism (PE). Risk may be higher if testosterone raises hematocrit or if you have other clot risks. Go to urgent care for sudden shortness of breath, chest pain, fainting, or one leg swelling and pain.
Worsening sleep apnea
Testosterone may worsen obstructive sleep apnea in some men, especially those with risk factors such as obesity. Signs include loud snoring, witnessed breathing pauses, and daytime sleepiness. Tell your clinician if these symptoms start or worsen after beginning therapy.
Mood changes and irritability
Some people report mood swings, irritability, or changes in energy. These symptoms can have many causes, including sleep disruption, stress, or other medical conditions. If you feel unusually agitated, depressed, or unsafe, contact a clinician promptly or seek urgent help.
Prostate related symptoms
Testosterone can worsen benign prostatic hyperplasia symptoms such as weak stream or frequent urination, and labeling advises prostate monitoring in appropriate patients. Tell your clinician about new urinary symptoms or blood in urine. Prostate cancer screening decisions should be individualized.
High blood pressure
Some testosterone products can increase blood pressure, which matters if you already have hypertension or cardiovascular risk. If you see consistently higher readings or develop headaches, chest discomfort, or vision changes, contact your clinician. Do not ignore very high readings with symptoms.
Gel transfer to others (topicals)
Testosterone gel can transfer to another person through skin contact, which can cause unwanted exposure. This is especially important around children and pregnant people. Follow the product specific instructions to reduce transfer risk and contact a clinician if someone else develops signs of androgen exposure.
When to call a clinician or seek urgent care
| If you notice | What it could mean | What to do |
|---|---|---|
| Sudden chest pain, shortness of breath, fainting, coughing blood | Pulmonary embolism or heart event | Seek emergency care immediately |
| One leg swelling, warmth, redness, or pain | Deep vein thrombosis (blood clot) | Seek urgent evaluation the same day |
| Face droop, arm weakness, trouble speaking, sudden severe headache | Stroke warning signs | Call emergency services immediately |
| Severe swelling, rapid weight gain, new shortness of breath | Fluid retention or heart strain | Call your clinician promptly |
| Very high blood pressure readings with headache or vision changes | Hypertensive urgency or other complication | Seek urgent care and contact your clinician |
| New urinary blockage, blood in urine, or new breast lump | Prostate or breast issue needing evaluation | Schedule prompt clinician evaluation |
Practical ways to reduce risk
Get baseline and follow up labs
Ask what your clinician will monitor, including hematocrit and testosterone level.
Bring up fertility goals early
If you want children, discuss options before starting testosterone therapy.
Track blood pressure at home
Share trends with your clinician, especially after starting or changing therapy.
Watch for clot warning signs
Know the red flags: chest pain, sudden shortness of breath, one leg swelling.
Prevent gel transfer
Follow the product instructions to avoid exposing partners or children.
Frequently Asked Questions
What are the most common testosterone side effects?
Common testosterone side effects can include acne or oily skin, swelling from fluid retention, and changes in mood or libido. Some men also notice breast tenderness or enlargement. If symptoms are new or worsening, discuss them with your clinician.
What are the side effects of testosterone injections?
Testosterone injections can cause the same systemic risks as other forms, including higher hematocrit, blood pressure changes, and possible clot risk. Injection products can also cause local reactions like pain or swelling at the injection site. Seek urgent care for chest pain, sudden shortness of breath, or one leg swelling.
Are testosterone gel side effects different from shots?
Many risks overlap across forms, but gels have an added concern: testosterone can transfer to others through skin contact. Product labeling includes steps to reduce transfer risk. Talk with your clinician if you have children or close skin to skin contact at home.
Can testosterone therapy affect fertility in men?
Yes. Testosterone therapy can suppress sperm production and may reduce fertility while you are using it. If fertility is important to you, bring it up before starting therapy so a clinician can discuss alternatives and monitoring.
How can I tell if my testosterone side effects are serious?
Treat symptoms like chest pain, sudden shortness of breath, fainting, one leg swelling, or stroke like symptoms as emergencies. Also contact a clinician promptly for severe swelling, very high blood pressure readings with symptoms, or new urinary blockage. When in doubt, get evaluated rather than waiting.