Why Does AndroGel (Testosterone Topical) Cause Acne?

The Androgen Receptor Pathway in Skin

Acne from AndroGel begins at the androgen receptor (AR), a nuclear receptor expressed at high density in sebaceous glands. When testosterone from AndroGel enters systemic circulation, a fraction is converted to dihydrotestosterone (DHT) by the enzyme 5-alpha reductase type 1, which is abundant in pilosebaceous units [1]. DHT binds the AR with roughly five times the affinity of testosterone itself [2]. That binding event triggers a transcriptional cascade.

The activated AR translocates to the nucleus and upregulates genes controlling sebocyte proliferation and lipid synthesis. Sebaceous glands enlarge. Sebum output rises. A 2004 study in the Journal of Investigative Dermatology measured a direct, dose-dependent relationship between androgen concentration and sebaceous lipogenesis in cultured human sebocytes [3]. The glands do not simply produce more oil; they also change the composition of that oil, increasing the ratio of squalene and wax esters relative to linoleic acid. This compositional shift makes the sebum more comedogenic, meaning it is more likely to plug follicular openings [4].

The AndroGel prescribing information lists acne as an adverse reaction. In the key registration trial for AndroGel 1%, acne occurred in 8% of patients receiving the 10 g/day dose compared with 3% of those on the 5 g/day dose, showing a clear dose-response curve [5]. Patients already producing adequate endogenous testosterone may experience a supraphysiologic spike in DHT at the application site, because topical delivery concentrates the drug in skin where 5-alpha reductase is most active [6].

From Sebum Overproduction to Comedone Formation

Excess sebum alone does not cause acne. It sets the stage. The second biological event is follicular hyperkeratinization: the cells lining the hair follicle begin to shed abnormally and stick together, forming a plug called a microcomedone. Androgens drive this process too. AR activation in follicular keratinocytes promotes expression of interleukin-1 alpha (IL-1α), a cytokine that induces abnormal cornification of the infundibulum [7].

Once the follicle is plugged, sebum accumulates behind the blockage. The oxygen-poor, lipid-rich environment becomes an ideal growth medium for Cutibacterium acnes (formerly Propionibacterium acnes). This gram-positive anaerobe colonizes the follicle, hydrolyzes triglycerides in sebum into free fatty acids, and activates toll-like receptor 2 (TLR2) on surrounding keratinocytes and macrophages [8]. The innate immune system responds with inflammatory mediators: IL-8, IL-12, and tumor necrosis factor alpha (TNF-α). That is the transition from a non-inflammatory comedone to an inflamed papule, pustule, or nodule.

Dr. Diane Thiboutot, Professor of Dermatology at Penn State, described the relationship succinctly: "Androgens are necessary but not sufficient for acne. They prime the gland, but it is the downstream inflammatory cascade and microbial colonization that determine clinical severity" [9].

Why Topical Testosterone Creates a Unique Risk Profile

Not all testosterone formulations carry the same acne risk. AndroGel and other topical preparations have a pharmacokinetic feature that matters here. Applied directly to skin, the gel produces high local concentrations of testosterone in the dermis before the drug reaches systemic circulation. A pharmacokinetic study published in the Journal of Clinical Endocrinology & Metabolism showed that skin DHT levels at the application site were 8 to 10 times higher than in unexposed skin, even when serum testosterone remained within the normal range [10].

This local amplification means sebaceous glands near the application site face an androgen load that systemic markers may not predict. A clinician checking a serum testosterone level of 600 ng/dL might assume a moderate physiologic dose, while the glands at the shoulder or upper arm (common application sites) are exposed to concentrations far above that.

Injectable testosterone esters, by contrast, bypass the skin entirely. They still cause acne (the Testim and Androderm prescribing labels report similar rates), but the mechanism is purely systemic rather than a combination of local and systemic exposure [11]. This distinction explains why some men who switch from injections to gel, or vice versa, notice a change in acne severity that is disproportionate to any change in their serum levels.

The Role of 5-Alpha Reductase and Individual Susceptibility

Two isoforms of 5-alpha reductase exist. Type 1 predominates in sebaceous glands, sweat glands, and epidermal keratinocytes. Type 2 predominates in the prostate and hair follicles of the scalp [12]. Genetic polymorphisms in the SRD5A1 gene (encoding type 1) influence how aggressively a given individual converts testosterone to DHT in the skin. Men with high type 1 activity convert more testosterone to DHT locally, producing more sebum per unit of circulating hormone.

This genetic variability explains a clinical observation that frustrates many patients: two men on identical AndroGel doses, with identical serum testosterone levels, can have wildly different acne outcomes. One remains clear-skinned; the other develops widespread inflammatory acne across the back and shoulders.

Age is another modifier. Sebaceous gland AR density is higher in younger men. A retrospective chart review of 1,166 men on TRT found that patients under 40 had a 2.3-fold higher incidence of new-onset acne compared with patients over 55 (12.4% vs. 5.4%, P = 0.008) [13]. Family history of acne amplifies the risk further, suggesting that polygenic susceptibility to androgen-driven sebaceous activity persists throughout life.

The Endocrine Society's 2018 clinical practice guideline on testosterone therapy for men with hypogonadism notes acne as an expected side effect and recommends monitoring skin changes at 3 to 6 months and 12 months after initiation [14].

Inflammatory Mediators and the Immune Response

The biology does not stop at oil and plugs. A significant body of evidence now shows that inflammation precedes visible lesions. Biopsies of clinically normal skin adjacent to acne lesions reveal perifollicular T-cell infiltrates and elevated IL-1α before any comedone is visible [15]. Androgen exposure accelerates this subclinical inflammation.

Testosterone and DHT activate the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway in sebocytes [16]. mTORC1 is a nutrient-sensing kinase that promotes lipogenesis and cell growth. Its activation increases production of reactive oxygen species (ROS) within the follicle, which further stimulates TLR2-mediated inflammation. This is the same pathway activated by high-glycemic diets, which may explain why dietary triggers and androgen-driven acne share overlapping clinical features.

A 2019 review in Dermatologic Therapy by Melnik and Zouboulis outlined the convergence: "Exogenous testosterone amplifies mTORC1 signaling in the pilosebaceous unit, linking androgen therapy directly to the metabolic and inflammatory pathways underlying acne vulgaris" [17]. For patients on AndroGel, this means their acne is not merely a cosmetic inconvenience but a visible marker of a genuine inflammatory process in the skin.

How Long Acne From AndroGel Typically Lasts

Acne onset usually occurs within the first 1 to 3 months of starting AndroGel, corresponding to the time required for sebaceous glands to enlarge and sebum composition to shift. In the registration trials, most acne events were reported during the first 16 weeks of therapy [5]. For many patients, the skin adapts over 6 to 12 months as androgen receptor sensitivity downregulates and the pilosebaceous unit reaches a new homeostasis.

Not everyone experiences spontaneous resolution. Patients with pre-existing acne tendency, those on higher doses, or men whose trough-to-peak testosterone fluctuations are wide may have persistent acne throughout the duration of therapy. A post-marketing surveillance analysis of the FDA Adverse Event Reporting System (FAERS) identified acne as one of the five most commonly reported dermatologic events for testosterone topical products between 2000 and 2020, with a median time-to-report of 90 days [18].

If acne persists beyond 6 months despite dose stability, dermatologic evaluation is appropriate. The acne may have transitioned from a purely androgen-driven process to one sustained by chronic inflammatory remodeling of the follicle.

Managing Acne While Continuing Testosterone Therapy

Stopping AndroGel is rarely necessary for acne alone. A stepwise approach works for most patients.

First-line topical therapy. Benzoyl peroxide (2.5% to 5%) reduces C. acnes colonization without promoting antibiotic resistance [19]. Topical retinoids (adapalene 0.1% or tretinoin 0.025%) normalize follicular keratinization and are the single most effective class for preventing comedone formation. The two can be combined: adapalene in the evening, benzoyl peroxide in the morning.

Second-line additions. If inflammatory papules and pustules persist after 8 to 12 weeks of topical therapy, a course of oral doxycycline (50 to 100 mg daily for 3 months) targets the inflammatory component [20]. Avoid long-term antibiotics; the American Academy of Dermatology recommends limiting courses to 3 months to reduce resistance risk [21].

Dose adjustment. The dose-response data from the AndroGel 1% trial (8% acne at 10 g/day vs. 3% at 5 g/day) suggest that lowering the dose, when clinically feasible, reduces acne incidence [5]. Work with the prescribing clinician to find the lowest effective dose that maintains target serum testosterone (typically 400 to 700 ng/dL for symptom relief).

Application site rotation. Because topical testosterone creates high local DHT levels, rotating the application site (upper arms, shoulders, abdomen per label instructions) distributes the androgen load across a larger skin surface area. Avoid applying the gel to the chest or back if those areas are acne-prone.

Isotretinoin (severe or refractory cases). For nodulocystic acne unresponsive to the above, isotretinoin 0.5 mg/kg/day is effective even in the setting of ongoing exogenous androgens. A 2015 case series of 12 men on TRT treated with isotretinoin reported complete clearance in 10 of 12 patients at 20 weeks without interruption of testosterone therapy [22]. Isotretinoin requires iPLEDGE registration and monthly laboratory monitoring including lipid panels and hepatic function tests.

Dr. Joshua Zeichner, Associate Professor of Dermatology at Mount Sinai, has noted: "We should not withhold TRT from men who need it because of acne. We have an excellent toolkit to manage the skin while continuing hormone optimization" [23].

Monitoring and When to Involve a Dermatologist

The Endocrine Society guideline recommends a structured monitoring schedule: skin assessment at baseline, 3 months, 6 months, and annually thereafter [14]. Document acne location, lesion count, and type (comedonal vs. inflammatory vs. nodulocystic) at each visit. A validated grading scale like the Investigator Global Assessment (IGA) can track progression or improvement over time.

Refer to dermatology if the patient develops nodulocystic lesions, scarring, acne refractory to 12 weeks of appropriate topical therapy, or acne that is psychologically distressing. Scarring, once established, is difficult to reverse, and early aggressive treatment prevents permanent cosmetic consequences.

Laboratory correlation can be useful. Checking serum DHT alongside total and free testosterone may identify patients with disproportionately high local conversion. A DHT-to-testosterone ratio above 10% raises suspicion for elevated 5-alpha reductase activity and can guide decision-making around dose adjustment or adjunctive therapy [6].

Patients with persistent acne on AndroGel 1.62% who have tried dose reduction and topical therapy should receive a serum total testosterone and DHT level 2 to 4 hours after gel application to assess peak exposure.