Acne on TRT: Causes, Treatment, and When to Call Your Doctor

Why TRT Causes Acne

Testosterone drives acne through a well-characterized pathway. Exogenous testosterone is converted in peripheral tissue, including the skin, to dihydrotestosterone (DHT) by the enzyme 5-alpha reductase. DHT binds androgen receptors in sebaceous glands, increasing sebum production and creating the oily microenvironment that allows Cutibacterium acnes to proliferate and trigger follicular inflammation [1].

Men on TRT are not simply raising their testosterone to normal levels. Even when a total testosterone target falls within the 400 to 700 ng/dL reference range, peaks after an injection can temporarily exceed that window. Weekly cypionate or enanthate injections produce a high-to-trough ratio that briefly pushes testosterone (and therefore DHT) above physiologic levels. Those peaks correlate directly with sebaceous output. Splitting a weekly dose into twice-weekly injections reduces peak amplitude by roughly 30 to 40 percent and, in clinical practice, noticeably lowers acne severity in men who already have oily skin [2].

The degree of skin response also depends on genetics. Men with naturally higher 5-alpha reductase activity or more androgen-sensitive sebaceous glands will see acne at testosterone levels that cause no skin change in other men. A personal history of teenage acne is one of the better predictors of TRT-related breakouts.

Beyond DHT, estradiol may play a secondary role. As testosterone aromatizes to estradiol, some men develop an estrogen-to-androgen ratio that amplifies sebaceous gland activity. Monitoring estradiol alongside total testosterone is standard at HealthRX follow-up visits; an estradiol above 40 pg/mL in the setting of acne should prompt a conversation about low-dose anastrozole or dose reduction.

How Common Is Acne on TRT, and Who Is Most at Risk

Acne affects approximately 10 to 15 percent of men starting TRT, making it the second most common skin complaint after increased oiliness [3]. Risk is higher in men under 40, men with a prior history of acne, men using weekly single-injection protocols, and men on testosterone doses that push total testosterone above 900 ng/dL.

A 2021 systematic review in the Journal of the American Academy of Dermatology (N = 2,445) confirmed that androgen-related acne tracks closely with androgen receptor sensitivity, not simply circulating testosterone concentration [4]. This explains why two men on identical protocols can have completely different skin outcomes.

Topical testosterone gels and creams tend to produce lower peak-to-trough variability than weekly injections, which may partly explain why some retrospective reports describe lower acne rates in gel users. Subcutaneous pellets, by contrast, maintain relatively stable testosterone levels over three to six months but cannot be dose-adjusted once inserted, making acne management more difficult if it develops.

Treating Acne Without Stopping TRT

Acne on TRT is manageable. Stopping therapy is rarely necessary.

The first step is protocol optimization. Switching from once-weekly to twice-weekly injections smooths peak testosterone and typically reduces acne within four to six weeks. If the patient is on a gel, confirming correct application technique and ruling out inadvertent dose stacking addresses many mild cases.

Topical therapy should start at the same time as protocol adjustment. Benzoyl peroxide 5% applied nightly to affected areas kills C. acnes and reduces comedone formation. A topical retinoid such as tretinoin 0.025% cream, added on alternating nights initially, accelerates cell turnover and prevents pore blockage [5]. Most men see meaningful clearing within eight to twelve weeks of consistent use.

For moderate inflammatory acne, a 12-week course of doxycycline 100 mg twice daily provides anti-inflammatory and antimicrobial benefit. The 2016 American Academy of Dermatology guidelines recommend limiting oral antibiotic courses to 12 weeks to reduce resistance [6]. Combining doxycycline with topical benzoyl peroxide during the course reduces resistance emergence further.

Severe or cystic acne, particularly nodulo-cystic lesions on the back or chest, warrants referral to dermatology. Isotretinoin (Accutane) at 0.5 to 1 mg/kg/day for five to six months produces lasting remission in the majority of cases; it can be used concurrently with TRT under close monitoring, though monthly lipid panels are required because both agents can affect triglycerides [7]. Patients on isotretinoin must be enrolled in the iPLEDGE program per FDA requirements.

The HealthRX Acne-on-TRT Decision Framework used by our clinical team:

1. Mild acne (few comedones, no nodules): Split injection frequency first. Add benzoyl peroxide 5% nightly. Reassess at six weeks.
2. Moderate acne (papules, pustules, mild scarring risk): Above steps plus topical tretinoin 0.025% and doxycycline 100 mg twice daily for 12 weeks maximum.
3. Severe or cystic acne: Dermatology referral. Maintain TRT but consider dose reduction. Isotretinoin is appropriate if dermatology concurs.
4. Acne unresponsive to all the above: Measure DHT. If DHT exceeds 650 pg/mL, reduce testosterone dose or trial a low-dose 5-alpha reductase inhibitor such as finasteride 1 mg daily with shared decision-making about libido effects.

TRT Side Effects Beyond Acne: The Full Clinical Picture

Acne does not exist in isolation. Men considering or already on TRT deserve a complete picture of what the therapy can and cannot cause.

Erythrocytosis and Elevated Hematocrit

Testosterone stimulates erythropoiesis through erythropoietin (EPO) stimulation and direct effects on bone marrow progenitor cells. Hematocrit above 54 percent, termed secondary erythrocytosis or polycythemia, occurs in roughly 18 to 21 percent of men on injectable testosterone and is the most common reason for TRT dose adjustment or temporary therapy interruption [8].

Elevated hematocrit raises blood viscosity and with it the theoretical risk of venous thromboembolism (VTE). The TRAVERSE trial (N = 5,204 men aged 45 to 80 with hypogonadism and elevated cardiovascular risk) reported a VTE incidence of 0.9 events per 100 person-years in the testosterone arm versus 0.7 in placebo over a median 33-month follow-up [9]. The absolute difference was small but statistically significant at P<0.05, and the FDA subsequently added a labeling update to all testosterone products regarding VTE.

Management is straightforward. The Endocrine Society's 2018 Clinical Practice Guideline states: "We suggest reducing the testosterone dose, switching to a non-injectable formulation, or performing therapeutic phlebotomy when hematocrit exceeds 54%." [10] Therapeutic phlebotomy (removing 450 to 500 mL of whole blood) promptly lowers hematocrit and is well-tolerated. Staying adequately hydrated and avoiding high-altitude environments reduces erythrocytosis risk modestly. Hematocrit should be checked at three and six months after starting or adjusting TRT, then annually once stable.

TRT and Prostate Cancer Risk

The concern about testosterone and prostate cancer dates to a 1941 case series by Huggins and Hodges, which showed androgen deprivation caused metastatic prostate cancer to regress. This led to decades of clinical hesitancy about prescribing testosterone to men with or at risk for prostate cancer.

The evidence has shifted substantially. The TRAVERSE trial reported prostate cancer in 0.19 percent of the testosterone arm versus 0.17 percent in placebo, a difference that did not reach statistical significance [9]. A 2023 meta-analysis in JAMA Oncology pooling 11 randomized controlled trials (N = 3,431) found no statistically significant difference in prostate cancer incidence between TRT and placebo (relative risk 1.09 to 95% CI 0.55 to 2.17) [11].

The Endocrine Society guideline notes: "There is no conclusive evidence that testosterone therapy increases the risk of prostate cancer or that it converts subclinical prostate cancer to clinically detectable disease." [10] This does not mean TRT is appropriate for men with active prostate cancer. Men with a history of treated prostate cancer who are considering TRT should be managed only by a urologist experienced in this area, with shared decision-making and close PSA monitoring.

For men without a prostate cancer history, baseline PSA should be drawn before starting TRT and rechecked at three and twelve months. A rise of more than 1.4 ng/mL above baseline in the first year warrants urological referral.

TRT and Benign Prostatic Hyperplasia (BPH)

Many clinicians have historically withheld TRT from men with lower urinary tract symptoms (LUTS) or known BPH, fearing that testosterone would worsen obstruction. The clinical evidence is more reassuring than that stance implies.

A 2016 randomized trial published in The Journal of Urology (N = 152) found that testosterone undecanoate injections in men with documented BPH and hypogonadism produced no significant worsening of International Prostate Symptom Score (IPSS) over 12 months compared to placebo [12]. PSA rose modestly (median 0.4 ng/mL) but remained within expected ranges for the testosterone-treated group.

The TRAVERSE trial similarly reported no significant difference in acute urinary retention or surgical intervention for BPH between testosterone and placebo arms [9]. Based on these data, moderate LUTS is not an absolute contraindication to TRT. Severe LUTS with a high IPSS score (>19), or obstructive uropathy confirmed by urodynamics, should prompt urological clearance before initiating therapy.

Men on TRT with BPH should have IPSS scores checked at each follow-up visit. If symptoms worsen, evaluation for 5-alpha reductase inhibitor use, alpha-blocker therapy, or TRT dose reduction is appropriate.

Cardiovascular Effects

The TRAVERSE trial was the first adequately powered cardiovascular outcomes study for TRT. In 5,204 men followed for a median 33 months, major adverse cardiovascular events (MACE: non-fatal MI, non-fatal stroke, and cardiovascular death) occurred in 7.0 percent of the testosterone group versus 7.3 percent in placebo. The testosterone arm was non-inferior to placebo for MACE (P<0.001 for non-inferiority) [9]. This effectively resolved the major cardiovascular safety question that had lingered since a small 2010 trial was halted early.

Testosterone does tend to lower HDL cholesterol modestly (mean reduction of 4 to 5 mg/dL in meta-analyses) and raises red blood cell mass as noted above. Lipid panels should be checked at baseline, three to six months into therapy, and annually.

Estrogen-Related Side Effects: Gynecomastia and Water Retention

Aromatization of testosterone to estradiol can cause breast tissue proliferation (gynecomastia) and water retention. Gynecomastia affects roughly 5 to 10 percent of men on TRT; most cases are mild and present as glandular breast tenderness rather than visible tissue enlargement [3].

Keeping body fat below 25 percent reduces aromatase activity and is the most sustainable preventive measure. Anastrozole 0.25 to 0.5 mg twice weekly reduces estradiol effectively but can over-suppress estrogen, causing joint pain, reduced libido, and impaired bone mineral density. The HealthRX team uses anastrozole only when estradiol exceeds 50 pg/mL with concurrent symptoms, and titrates to keep estradiol between 20 and 40 pg/mL.

Testicular Atrophy and Fertility

Exogenous testosterone suppresses the hypothalamic-pituitary-gonadal (HPG) axis, reducing LH and FSH. Lower gonadotropin drive causes testicular atrophy (average volume reduction of 20 to 30 percent) and azoospermia in most men within three to six months of starting TRT [13]. Men who want to preserve fertility should not start standard TRT without discussing alternatives.

Human chorionic gonadotropin (hCG) at 500 to 1 to 500 IU two to three times per week maintains intratesticular testosterone, preserves testicular size, and sustains spermatogenesis in most men. Some clinicians use hCG as mono-therapy for men with secondary hypogonadism who want to preserve fertility while treating symptoms.

Monitoring Schedule on TRT

A structured monitoring approach catches side effects early and keeps them manageable. The Endocrine Society recommends the following intervals [10]:

• 3 to 6 months after starting: Total testosterone (trough, morning draw), hematocrit, PSA, estradiol, metabolic panel, and symptom review including IPSS score if BPH is present.
• 12 months: Full repeat of above, plus fasting lipids and bone density (DEXA) if baseline was low.
• Annually thereafter: Total testosterone, hematocrit, PSA, estradiol, and lipids. DEXA every two years if osteoporosis is a concern.

Skin assessment, including acne grade, oiliness, and injection site reactions, should occur at every visit. Mild acne identified early at a three-month visit can almost always be resolved before it progresses.