Where to Put Testosterone Gel: Application & Safety

Testosterone gel is typically applied once daily to the upper arms, shoulders, or abdomen, though the exact approved sites vary by product. The choice of application site matters more than most people realize: where you put the gel can change how much testosterone your body actually absorbs by as much as 30 to 40 percent, and applying it carelessly can expose partners, children, and even pets to unwanted hormonal effects. Getting the basics right protects both your treatment results and the people around you.

Which Body Sites Are Used and Why They Differ

The most commonly prescribed application sites are the upper arms and shoulders, the abdomen, and for certain formulations, the underarm area. All three will raise testosterone levels into the normal range for most men with low testosterone, but the amount that actually reaches your bloodstream varies depending on where the gel goes. A crossover study comparing the same 1.62% gel applied to the abdomen versus the upper arms and shoulders found that abdominal application produced roughly 30 to 40 percent lower bioavailability than the upper arms and shoulders.¹ In practice, that means a man applying gel to his belly might absorb meaningfully less testosterone than one rubbing it into his shoulders, even though the dose on the tube is identical.

A separate study testing a 1% gel (Testim) across the abdomen, calf, and leg found that the abdomen delivered the highest testosterone levels, followed by the calf, with the leg trailing behind.² These two studies seem contradictory at first glance, but they used different gel formulations, and formulation chemistry heavily influences skin absorption. The takeaway is straightforward: you should always apply the gel to the site specified in your product’s prescribing information, because that is the site where the dose was calibrated during testing.

The underarm (axillary) route deserves its own mention. One formulation (Axiron) is specifically designed for the armpit, and studies show that axillary application produces about twice the bioavailability of inner-arm application for the same testosterone solution.³ The thin, warm, moist skin of the armpit absorbs the drug more efficiently. But you should not apply a gel labeled for the arms to your armpit or vice versa, because the dose and vehicle are matched to a specific site.

How Much Actually Gets Through the Skin

Regardless of site, transdermal testosterone is not especially efficient. Long-term pharmacokinetic data from a 180-day study of a 1% hydroalcoholic gel applied to the upper arms, shoulders, and abdomen found that only about 9 to 14 percent of the applied testosterone was bioavailable.⁴ Most of the hormone sits on the skin surface or gets trapped in the outer skin layers, which is part of why secondary transfer to other people is such a concern. The upside of that slow, steady absorption is stable blood levels: serum testosterone typically reaches a steady state within two days of daily application and stays there as long as you keep using the gel consistently.

One practical question men often ask is whether spreading the gel over a larger skin area helps. A study comparing application at one site versus four sites (both arms/shoulders plus both sides of the abdomen) found only a modest, non-significant increase of about 23 percent in the area under the curve when using four sites.⁵ So spreading the same dose across a wider area does not dramatically boost absorption. Follow the product instructions on surface area and do not overthink it.

Scrotal Application and the DHT Question

Scrotal skin absorbs topical testosterone far more readily than non-scrotal skin. A pharmacokinetic study of testosterone cream applied to the scrotum found that a 25 mg dose (much lower than the 50 to 100 mg typically used on other sites) produced a swift, dose-dependent rise in serum testosterone that maintained physiological levels for about 16 hours.⁶ This efficiency is well known in dermatology: scrotal skin is thin, highly vascularized, and lacks the thick outer layer that slows absorption elsewhere.

However, scrotal application also raises dihydrotestosterone (DHT) levels more than non-scrotal sites do. The same study showed a time-dependent increase in serum DHT peaking a couple of hours after testosterone peaked. Some clinicians have experimented with scrotal application for this reason, but most commercially available testosterone gels are not approved or dosed for scrotal use. The skin irritation profile also differs, and products containing alcohol-based vehicles can cause significant discomfort on scrotal tissue. If your provider recommends scrotal application, they will typically prescribe a compounded cream rather than a standard gel, and the dose will be substantially lower than what you would use on your arms or abdomen.

When You Shower Matters

Showering too soon after applying testosterone gel can wash away a large portion of the dose before it absorbs. A study found that showering just 15 minutes after applying 50 mg of gel dropped average plasma testosterone levels dramatically compared with not showering, and showering at 30 minutes still produced unacceptably low levels in most users.⁷ The practical rule most prescribers give is to wait at least two hours before getting the application site wet.

But what happens if you need to wash later in the day? A separate study looked at washing the application site at two, six, and ten hours after applying a 1.62% gel. Washing at two or six hours caused a modest 10 to 14 percent decrease in testosterone levels over 24 hours, while washing at ten hours had no measurable effect at all.⁸ That same study found that washing removed at least 81 percent of the testosterone remaining on the skin surface, which is important for reducing transfer risk. So the ideal routine is to apply the gel in the morning, let it dry and absorb for a few hours, and wash the site before close contact with others later in the day.

Secondary Transfer and Who Is at Risk

Secondary transfer is the most serious safety concern with testosterone gel. The residue left on your skin after application can transfer testosterone to anyone who touches that area, and the consequences are not trivial. A case report described prenatal virilization in a female infant caused by secondary maternal exposure to the father’s testosterone gel, along with postnatal virilization in the infant’s twin sister.⁹ Children who come into repeated skin contact with a gel user can develop signs of early puberty, including genital enlargement, body hair growth, and advanced bone age.

Transfer research has quantified the risk with some precision. A study measuring testosterone levels in women after direct skin-to-skin contact with a man’s gel application site found that testosterone exposure increased by up to 280 percent from baseline when a higher gel dose was used, though average levels stayed within the normal female range in that controlled setting.¹⁰ Transfer was higher from the upper arms and shoulders than from the abdomen, likely because the abdomen is easier to cover with clothing. When the application site was washed before contact, average testosterone levels in the women were comparable to baseline.

Pets are also vulnerable. A review of adverse events in animals found clinically relevant consequences in dogs and cats after secondary exposure to topical hormones, with cats appearing particularly sensitive.¹¹ If you have a cat or dog that likes to curl up against your bare skin, this deserves serious attention.

Practical Steps to Prevent Transfer

Three strategies reduce transfer: covering the site with clothing, washing before contact, and choosing application sites that are easily concealed. The evidence supports all three.

Covering the application site with a t-shirt after the gel dries is remarkably effective. One study found that a t-shirt barrier completely prevented transfer when gel was applied to the upper arms and shoulders, reducing any increase in contact-person testosterone to roughly 5 to 11 percent above baseline, which is essentially negligible.¹² When the gel was applied to the abdomen, a t-shirt reduced transfer by about 40 to 48 percent but did not eliminate it completely, probably because shirt fabric sits looser over the belly and makes intermittent skin contact. The practical conclusion: a snug-fitting shirt over the application site is one of the simplest and most effective precautions you can take.

Washing the application site before anticipated contact is the other reliable safeguard. As noted in the showering data, washing at two hours post-application removes the vast majority of surface testosterone while only modestly reducing your absorbed dose. In vitro modeling using porcine skin has confirmed the basic pattern: the longer you wait after application, the less testosterone remains available for secondary transfer, because more of it has either absorbed or dried on the surface in a less-transferable state.¹³

A reasonable daily routine for someone living with a partner or children: apply the gel in the morning, let it dry for a few minutes, put on a shirt, and wash the site with soap and water before any skin-to-skin contact. If you have young children or a pregnant partner, be especially strict. The case reports in the medical literature almost always involve gel users who did not know about the transfer risk or did not take precautions consistently.

Blood Draws and False Readings

Here is a problem that trips up both patients and doctors: if you apply testosterone gel to your arms and then have blood drawn from a vein in your arm, residual gel on the skin can contaminate the sample and produce falsely sky-high testosterone readings. Case reports describe this happening when gel was applied at or near the venipuncture site on the day of blood sampling, with subsequent draws from an uncontaminated site showing levels right in the therapeutic range.¹⁴

A retrospective review confirmed this is not rare and recommended that serum testosterone be measured at least eight hours after the last gel application to avoid artifact.¹⁵ Another recent analysis urged clinicians and lab staff to stay alert to this common form of contamination and to instruct patients to avoid applying gel near the planned blood draw site.¹⁶

If you use testosterone gel on your arms and have a blood draw coming up, either apply the gel to a different site (like the abdomen) for a day or two before the draw, or at minimum wash the arm thoroughly and make sure the phlebotomist knows you use topical testosterone. A false high reading can lead your doctor to lower your dose unnecessarily or investigate a problem that does not exist.

Skin Reactions Compared With Patches

If you have used testosterone patches in the past and dealt with skin irritation, gels are generally a step up. Application site reactions like redness, itching, and blistering are a well-known drawback of testosterone patches, and they occur less frequently with gel formulations.¹⁷ Gel users sometimes report mild dryness or irritation, especially if they apply to the same small patch of skin every day, but rotating between approved sites within the labeled area (for example, alternating between left and right shoulders) helps. Products with higher alcohol concentrations can sting on broken skin, so avoid areas with cuts, rashes, or sunburn.

Compared with patches, gels also produce a different hormonal profile. A head-to-head pharmacokinetic study found that nightly patch application mimicked the natural circadian rhythm of testosterone, while morning gel application produced a flatter daily profile with more variable individual peaks.¹⁸ That same study found that DHT levels and the DHT-to-testosterone ratio were two to three times higher with gel than with patches. The clinical significance of that difference remains debated, but it is worth knowing if your provider is tracking your DHT.

Monitoring Beyond Testosterone Levels

Testosterone therapy, regardless of the delivery method, can stimulate red blood cell production. Clinical guidelines recommend checking hemoglobin and hematocrit before starting treatment, again at three to six months, and annually thereafter. If hematocrit rises above 54 percent, treatment should be paused until it drops back to a safe level, and restarted at a lower dose.¹⁹ This applies equally to gels, patches, and injections. Thick blood raises the risk of clotting events, so do not skip lab work even if you feel fine.

Why So Many Men Stop Using Gel

Adherence to topical testosterone therapy is surprisingly poor. A large retrospective claims analysis found that by six months, only about a third of men who started on gel were still using it, and by twelve months, that number had dropped to roughly 15 percent.²⁰ About half of the men who stopped eventually restarted, usually at the same dose. The pattern suggests that many men cycle on and off rather than sticking with consistent daily application.

A ten-year Korean observational study found that inconvenience was the most common reason gel users gave for quitting, ahead of cost, worry about side effects, and perceived lack of effect.²¹ That finding fits with the daily reality of gel use: you have to apply it at roughly the same time every morning, wait for it to dry, avoid showering for a while, cover the site, and worry about transferring it to family members. It is easy to see why injections every one to two weeks appeal to men who find the daily routine burdensome. Factors associated with better adherence included being prescribed by a specialist rather than a primary care doctor, suggesting that more detailed counseling about expectations and technique may help.²²

If you are struggling with the daily routine, it is worth having a frank conversation with your prescriber about alternative delivery methods rather than quietly skipping doses. Inconsistent gel use means erratic testosterone levels, which can leave you feeling worse than if you were on a steady regimen of any type.

Sites You Should Never Use

Product labels universally warn against applying testosterone gel to the genitals (unless specifically prescribed for scrotal application of a compounded cream), the chest, or any area that will come into direct contact with another person’s skin. The chest is a particular concern because casual contact during hugging or holding a child is almost unavoidable. Some men assume the inner thigh is a reasonable alternative, and while early pharmacokinetic work did test thigh application, current commercially available gels are not dosed or approved for the thigh.²³ Applying gel to an unapproved site means you have no reliable way to predict how much testosterone you are absorbing, which defeats the purpose of a carefully calibrated dose.

Broken or irritated skin should also be avoided. Open wounds or inflamed areas absorb testosterone faster and less predictably, and alcohol-based gel vehicles will sting. If you have eczema, psoriasis, or a sunburn on your usual application area, switch to another approved site or talk to your provider about timing.