Topical testosterone gels and patches carry the lowest cardiovascular risk among the major testosterone delivery methods. A large comparative study published in JAMA Internal Medicine found that injectable testosterone was associated with a 26% higher rate of cardiovascular events, a 16% higher rate of hospitalization, and a 34% higher rate of death compared to gels. Patches and gels had nearly identical risk profiles across all measured outcomes.
But “safest” depends on more than just heart risk. Each delivery method has its own trade-offs involving blood thickness, hormone stability, liver health, and even safety for people around you. Here’s what the evidence shows for each option.
Why Gels and Patches Come Out Ahead
Transdermal options (gels and patches applied to the skin) deliver testosterone at a slow, steady rate that mimics the body’s natural rhythm more closely than injections do. This steadier absorption matters because sharp spikes in testosterone levels are what drive many side effects, particularly the thickening of blood that can raise the risk of clots and stroke.
In a head-to-head comparison, 33% of men on injected testosterone developed elevated blood thickness (hematocrit at or above 50%), and 10% reached the danger zone of 54% or higher. Among men using a nasal testosterone gel, zero patients crossed either threshold. Injections raised hematocrit by an average of 3.24 percentage points more than the gel form, a clinically meaningful difference that often forces men on injections to donate blood periodically or reduce their dose.
For blood clot risk specifically, no single delivery method was statistically worse than another. The differences between forms show up most clearly in cardiovascular events and blood thickness.
Injections: Higher Risk but Widely Used
Intramuscular injections remain the most commonly prescribed form of testosterone, largely because they’re inexpensive and effective. The trade-off is a roller-coaster hormone pattern. Doctors typically prescribe large doses every two weeks to reduce how often you need a shot, but this creates pronounced peaks and troughs. You may feel great for the first few days after an injection, then sluggish and irritable as levels drop before the next one.
Subcutaneous injections (into the fat layer just under the skin rather than deep into muscle) are gaining traction as a way to smooth out this pattern. Because fat tissue has less blood flow and more predictable lymphatic drainage than muscle, testosterone absorbed from a subcutaneous injection reaches peak concentration more slowly (about 8 days versus 3.3 days for intramuscular). The result is more stable testosterone levels, easier self-administration with smaller needles, less pain, and no risk of sciatic nerve injury. Head-to-head safety trials comparing the two injection routes are still limited, but the pharmacology strongly favors subcutaneous delivery for steadier levels.
Oral Testosterone: No Longer a Liver Risk
Older oral testosterone formulations like methyltestosterone were notorious for causing liver damage. They passed directly through the liver before reaching the bloodstream, and the toxic byproducts accumulated with use. These older pills are essentially obsolete.
Newer oral formulations use a different compound, testosterone undecanoate, that gets absorbed through the lymphatic system in the gut, bypassing the liver almost entirely. Three FDA-approved versions are now available. No clinically significant liver toxicity has been reported with any of them, and gastrointestinal side effects are generally mild. These represent a genuine shift in oral testosterone safety, though long-term data covering decades of use don’t exist yet.
The Transfer Risk With Gels
Gels have one unique safety concern that doesn’t apply to other forms: they can transfer testosterone to partners, children, or pets through skin contact. Without any precautions, women who had prolonged skin-to-skin contact with a man’s gel application site saw their testosterone levels rise 86 to 185% above their normal baseline. One female study participant developed worsening acne from unprotected contact alone.
Two simple steps nearly eliminate this risk. Wearing a shirt over the application site reduced female partners’ testosterone exposure to levels within the normal range for women. Showering before contact was equally effective, dropping residual testosterone on the skin from a median of 127 micrograms to just 0.7 micrograms. If you live with a partner, children, or are in regular close physical contact with others, either covering the site or showering first makes gel use safe for those around you.
Cardiovascular Safety Overall
A landmark trial published in the New England Journal of Medicine tested whether testosterone therapy itself raises heart attack and stroke risk. In men who already had cardiovascular disease or were at high risk for it, testosterone was no worse than placebo: 7.0% of men on testosterone experienced a major cardiac event compared to 7.3% on placebo. The therapy did show slightly higher rates of atrial fibrillation, acute kidney injury, and pulmonary embolism, so cardiac monitoring still matters.
A separate meta-analysis of 41 randomized controlled trials confirmed that testosterone therapy was not associated with a statistically significant increase in major cardiac events. The current medical consensus is that testosterone is safe in the short to medium term for the heart, though long-term data spanning many decades are still accumulating.
Prostate Cancer and Testosterone
The old fear that testosterone fuels prostate cancer has not held up under rigorous study. The same 41-trial meta-analysis found no statistically significant increase in prostate cancer events among men on testosterone therapy. That said, monitoring remains standard practice. PSA (a prostate marker in blood) should be checked at least once a year, and every six months if you have a father or brother with prostate cancer history.
Compounded vs. FDA-Approved Products
All FDA-approved testosterone products, whether gels, patches, injections, or oral capsules, use bioidentical testosterone that is chemically identical to what your body makes. The term “bioidentical” doesn’t refer to a special or superior product. Some compounding pharmacies also make custom testosterone preparations, but these aren’t held to the same manufacturing standards. Dose and purity can vary from batch to batch, which introduces unnecessary risk when standardized, tested alternatives exist.
Routine Monitoring That Keeps Any Form Safe
Regardless of which delivery method you use, regular blood work is what transforms testosterone therapy from risky to manageable. Before starting, you need two early morning testosterone levels along with baseline checks of hemoglobin, hematocrit, PSA, and several hormones. At three months, your doctor should recheck testosterone and hematocrit to make sure levels are in range and your blood isn’t thickening. After that, these safety labs should be repeated every six months for as long as you’re on therapy. Total testosterone above 800 ng/dL is generally considered excessive, and prescriptions shouldn’t be refilled without lab results on file from the past six months.
The pattern is consistent across the evidence: transdermal gels and patches offer the gentlest safety profile, subcutaneous injections are a reasonable middle ground, and intramuscular injections carry the highest measurable risk among common options. Newer oral formulations have resolved the liver concerns that plagued earlier pills. Whichever form you use, consistent blood monitoring is what keeps the therapy safe over time.