Short answer: Testosterone is the main male sex hormone, prescribed to men with confirmed low testosterone caused by a medical condition (hypogonadism). It comes as gels, injections, patches, nasal gel, pellets, and pills. It is a Schedule III controlled substance because of misuse for muscle building. In 2025 the FDA removed heart attack and stroke language from its boxed warnings and added blood pressure warnings.
Key takeaways
- What it is: Testosterone is an androgen (anabolic steroid) and a Schedule III controlled substance in the US.
- Main uses: Male hypogonadism.
- Timing: effects start in days to weeks for symptom change and last depends on form.
- Most dangerous mix: Other anabolic steroids or stimulants (misuse), which can cause heart, liver, and blood pressure strain.
- Naloxone: it does not reverse this drug, but give it whenever opioids could be involved.
- Dependence risk: Low (therapeutic); moderate with misuse.
- Legal route: only with a prescription from a DEA-registered clinician, filled by a licensed pharmacy.
What is testosterone?
Testosterone is approved for men with low testosterone due to conditions of the testes, pituitary, or hypothalamus (primary or secondary hypogonadism), confirmed by symptoms and at least two low morning blood tests. Labels state it is not established for low testosterone due to aging alone.
Off-label, testosterone is used in gender-affirming hormone therapy for transgender men and, in low doses, for some women with low sexual desire.
Quick facts
| Fact | Testosterone |
|---|---|
| Generic name | Testosterone (cypionate, enanthate, undecanoate; gels and solutions) |
| Brand names | AndroGel, Testim, Depo-Testosterone, Xyosted, Aveed, Jatenzo, Kyzatrex, Tlando, Natesto |
| Drug class | Androgen; anabolic steroid |
| US legal status | Schedule III, prescription only |
| Approved uses | Male hypogonadism with confirmed low levels and symptoms |
| Forms | Gel, solution, injection, patch, nasal gel, pellets, capsules |
| Testing before treatment | Two low morning blood levels on separate days |
| Half-life | Depends on form: hours (gel) to weeks (undecanoate injection) |
| Key monitoring | Testosterone level, red blood cell count (hematocrit), blood pressure, prostate |
How long does testosterone last?
- Starts working: Days to weeks for symptom change
- Effects last: Depends on form
- Half-life: Depends on form: hours (gel) to weeks (undecanoate injection)
Timing varies with the dose, the form, how it is taken, liver and kidney function, age, and other drugs taken at the same time.
What are the biggest risks of testosterone?
The FDA requires boxed warnings, its strongest, on testosterone products, including:
- Gels and solutions: children and women can absorb testosterone from skin contact, causing early puberty, genital enlargement, or virilization.
- Xyosted and oral testosterone undecanoate: can raise blood pressure, which increases the risk of heart attack and stroke.
- Aveed: serious oil microembolism reactions and allergic reactions during or right after the injection.
2025 label changes: after the TRAVERSE trial found no increase in major heart events compared with placebo in men with hypogonadism, the FDA removed boxed warning language about increased heart attack and stroke risk, required a blood pressure warning on all testosterone products, and kept the limitation on use for age-related low testosterone.
Common side effects include acne, skin reactions at the application site, increased red blood cells, breast swelling, and reduced sperm count.
Serious risks include too many red blood cells (raising clot risk), worsening sleep apnea, blood clots in veins, worsening of urinary symptoms from an enlarged prostate, and infertility, since testosterone suppresses sperm production.
Warning: Testosterone suppresses sperm production and is not a treatment for infertility. Men who want children should discuss alternatives such as clomiphene or hCG with a specialist.
What should you never mix with testosterone?
| Combined with | What happens | Label guidance |
|---|---|---|
| Warfarin | Increases anticoagulant effect | Monitor INR |
| Insulin and diabetes medicines | Can lower blood sugar | Monitor glucose |
| Corticosteroids | More fluid retention | Use caution with heart or kidney disease |
| Other anabolic steroids or stimulants (misuse) | Heart, liver, and blood pressure strain | Avoid |
Check any combination with the DoseUses combination checker or ask a pharmacist.
What are the signs of a testosterone overdose, and what should you do?
Testosterone does not cause an acute overdose like opioids or sedatives. Harm comes from long-term high levels: high red blood cell counts, high blood pressure, blood clots, heart enlargement, mood changes, and aggression. Some injectable forms can cause sudden reactions during the injection.
When to get emergency help
- Call 911 for chest pain, sudden shortness of breath, signs of a stroke (face drooping, arm weakness, slurred speech), or fainting.
- Call 911 for coughing, throat tightness, or trouble breathing during or right after an injection.
- Get urgent care for a painful, swollen leg, which can signal a blood clot, or for yellowing of the skin or eyes.
- Call Poison Help at 1-800-222-1222 if a child has touched or swallowed a testosterone gel or other product.
What happens when you stop testosterone?
Prescribed testosterone does not cause withdrawal in the usual sense, but it switches off the body's own production. After stopping, symptoms of low testosterone can return for weeks to months while natural production recovers, and it may not fully recover after long or high-dose use.
- Weeks 1 to 4Levels fallFatigue, low mood, reduced sex drive, and hot flashes as levels drop.
- Months 1 to 3Recovery beginsThe brain restarts signals to the testes; symptoms of low testosterone peak.
- 3 to 12 months or moreNatural production returnsRecovery may be slow or incomplete after years of use or high doses.
See the withdrawal timelines and the full testosterone withdrawal guide.
Is testosterone legal?
In the United States, testosterone is a Schedule III controlled substance. The only legal way to get it is with a prescription from a clinician registered with the Drug Enforcement Administration (DEA), filled by a licensed pharmacy. Depending on state law, that can be a physician, nurse practitioner, or physician assistant.
- Refills: a Schedule III prescription can be refilled up to five times within six months of the date it was written. After that, a new prescription is needed.
- Telehealth: federal flexibilities let DEA-registered clinicians prescribe Schedule II to V medicines after a telemedicine visit, without a prior in-person exam, through December 31, 2026. A permanent DEA rule was under final review in late 2026. State rules can be stricter.
- Monitoring: prescribers and pharmacists in most states check a prescription drug monitoring program, a database of controlled-substance prescriptions, before prescribing or dispensing.
Outside the United States
| Country | Status |
|---|---|
| United Kingdom | Class C; possession for personal use without prescription not an offence, supply illegal |
| Canada | Schedule IV; prescription only |
| Australia | Schedule 4 prescription medicine; controlled in most states |
| International | Not under UN control; banned in sport by the World Anti-Doping Agency |
Frequently asked questions about testosterone
Does testosterone therapy increase heart attack risk?
The large TRAVERSE trial found no increase in major heart events in men with hypogonadism, and in 2025 the FDA removed that language from boxed warnings. It can raise blood pressure, which is now a class warning.
Can I get testosterone for low energy as I age?
Labels state testosterone is not established for age-related low testosterone without an underlying condition. Two low morning tests and symptoms are needed for diagnosis.
Does testosterone affect fertility?
Yes. It lowers sperm production and can cause infertility, usually reversible after stopping, but not always.
Is buying testosterone online legal?
Only with a prescription from a licensed clinician, filled by a licensed pharmacy. Products sold without a prescription are illegal and may be counterfeit or contaminated.
Sources
- AndroGel (testosterone) prescribing information, DailyMed, US National Library of Medicine.
- FDA issues class-wide labeling changes for testosterone products, US Food and Drug Administration, 2025.
- Anabolic Steroids, MedlinePlus, US National Library of Medicine.
- Controlled Substance Schedules, DEA Diversion Control Division.
- 21 CFR 1306.22, Refilling of prescriptions (Schedules III and IV), Electronic Code of Federal Regulations.
- Prescribing controlled substances via telehealth, US Department of Health and Human Services.
- BeSafeRx: Your Source for Online Pharmacy Information, US Food and Drug Administration.
- Safe Pharmacy, National Association of Boards of Pharmacy.
This guide summarizes the sourced DoseUses Testosterone profile, written from FDA labels, DEA rules, and federal health agencies. It is educational and is not medical advice. Last updated October 5, 2026.
