Can testosterone treatment cause discolouration in the skin? Testosterone replacement therapy (TRT) is prescribed for men with clinically confirmed hypogonadism to address symptoms including reduced libido, fatigue, and decreased muscle mass. Whilst skin discolouration is not commonly listed as a direct adverse effect in UK-licensed testosterone preparations, certain skin changes may occur during treatment. Application site reactions with transdermal formulations can cause localised redness or post-inflammatory hyperpigmentation, whilst androgenic effects may lead to acne-related pigmentation changes. Understanding these potential dermatological effects helps patients recognise expected side effects and identify changes requiring medical evaluation.

Can Testosterone Treatment Cause Skin Discolouration?

Testosterone replacement therapy (TRT) is prescribed for men with clinically confirmed hypogonadism, a condition characterised by low testosterone levels and associated symptoms. Whilst testosterone treatment can effectively address symptoms such as reduced libido, fatigue, and decreased muscle mass, patients may experience various dermatological side effects during therapy.

Skin discolouration is not commonly listed as a direct adverse effect of testosterone treatment in the Summary of Product Characteristics (SmPCs) for testosterone preparations licensed by the Medicines and Healthcare products Regulatory Agency (MHRA). However, certain skin changes can occur that may alter skin appearance or pigmentation indirectly. The most frequently reported dermatological reactions include acne, oily skin, and application site reactions (particularly with transdermal formulations).

It is important to distinguish between true pigmentary changes and other skin alterations. Application site reactions with testosterone gels or patches may cause localised erythema (redness), irritation, or post-inflammatory hyperpigmentation, which can appear as darkened patches where the product is applied. Additionally, testosterone's androgenic effects can stimulate sebaceous gland activity, potentially leading to acne or folliculitis, which may subsequently cause post-inflammatory pigmentation changes, particularly in individuals with darker skin tones.

Patients should be aware that whilst there is no established direct causal link between systemic testosterone therapy and widespread skin discolouration, any unexplained pigmentary changes warrant medical evaluation. Such changes could indicate unrelated dermatological conditions, allergic reactions, or rarely, underlying endocrine disorders that require investigation. Healthcare professionals should conduct a thorough assessment to determine the cause and appropriate management of any skin discolouration reported during testosterone treatment.

Types of Skin Changes During Testosterone Treatment

Testosterone therapy can produce several distinct types of skin changes, each with different underlying mechanisms. Understanding these variations helps patients and clinicians differentiate between expected side effects and changes requiring further investigation.

Application site reactions are common skin-related adverse effects, particularly with transdermal testosterone preparations (gels, patches, or creams). These reactions typically manifest as:

• Erythema and irritation: Redness, itching, or burning at the application site

• Contact dermatitis: Allergic or irritant reactions to the vehicle components or adhesive materials in patches

• Post-inflammatory hyperpigmentation: Darkened skin patches that may develop following repeated irritation or inflammation at application sites

Androgenic skin effects result from testosterone's physiological actions on skin structures. These include increased sebum production leading to oily skin and acne vulgaris. Acne lesions, particularly when inflamed or manipulated, can leave behind hyperpigmented marks (post-inflammatory hyperpigmentation), especially in individuals with darker skin tones.

Vascular changes may also occur, with some patients reporting increased facial flushing or a ruddy complexion due to testosterone's effects on erythropoiesis (red blood cell production) and potential polycythaemia. This gives skin a reddish appearance rather than true pigmentary change. If haematocrit rises to ≥0.54, treatment may need to be paused while causes are investigated.

Rare considerations include unusual pigmentary changes, particularly those resembling bronze discolouration, which warrant investigation for conditions such as haemochromatosis or Addison's disease. These conditions may coincidentally present during testosterone therapy but are not caused by it.

When to Seek Medical Advice About Skin Discolouration

Whilst mild skin changes during testosterone therapy may be expected, certain presentations require prompt medical evaluation to exclude serious underlying conditions or complications.

Seek urgent medical attention (contact your GP or NHS 111) if you experience:

• Widespread or progressive pigmentation changes: Darkening of skin across multiple body areas, particularly if accompanied by darkening of skin creases, mucous membranes, or new pigmented patches

• Bronze or metallic skin discolouration: This may indicate iron overload (haemochromatosis) or other metabolic disorders requiring investigation

• Yellowing of skin or eyes (jaundice): This could suggest hepatic dysfunction, which requires immediate assessment. While licensed UK testosterone formulations (transdermal/injectable) have low hepatic risk, jaundice always requires urgent evaluation

• Severe application site reactions: Blistering, severe pain, spreading redness, or signs of infection at application sites

• Skin changes with systemic symptoms: Pigmentation accompanied by fatigue, weight loss, dizziness, or gastrointestinal symptoms may indicate endocrine disorders such as Addison's disease. If experiencing severe vomiting, confusion, or dizziness with these symptoms, seek emergency care (999/A&E)

Arrange a routine GP appointment for:

• Persistent localised discolouration at application sites that does not resolve after changing application areas

• New or worsening acne that is affecting quality of life or causing scarring

• Any new moles or changes to existing moles (following the ABCDE rule: Asymmetry, Border irregularity, Colour variation, Diameter >6mm, Evolution/change)

• Skin changes causing significant concern or distress

Before your appointment, it is helpful to document when the skin changes began, their location and progression, any associated symptoms, and whether they correlate with testosterone administration timing. Bring a list of all medications, including over-the-counter products and supplements, as these may contribute to skin changes.

If you suspect your skin changes are related to testosterone treatment, you can report this through the MHRA Yellow Card Scheme, which helps monitor medication safety.

Managing Skin Side Effects on Testosterone Therapy

Effective management of skin-related side effects during testosterone therapy involves both preventative strategies and targeted interventions, often without requiring discontinuation of treatment.

For application site reactions, consider these evidence-based approaches:

• Rotate application sites systematically: Apply transdermal testosterone to different areas (as per product instructions) to allow skin recovery between applications

• Optimise skin preparation: Ensure skin is clean, dry, and free from lotions or oils before application; avoid applying to broken or irritated skin

• Consider formulation changes: If persistent reactions occur, discuss with your prescriber whether switching between gel, patch, or alternative delivery methods (such as intramuscular injections) might be appropriate

• Topical management: Mild hydrocortisone cream (1%, available over-the-counter) may help with minor irritation for short periods, though should not be applied immediately before testosterone application

For acne and oily skin, in line with NICE guidance (NG198):

• Gentle skincare routine: Use non-comedogenic cleansers and moisturisers; avoid harsh scrubbing which can worsen inflammation

• Topical treatments: Fixed-dose combination treatments (such as adapalene with benzoyl peroxide) are recommended first-line

• Oral therapies: For moderate to severe acne, oral antibiotics (such as lymecycline) may be prescribed for up to 3 months alongside topical treatments. Avoid antibiotic monotherapy. In resistant cases, referral to dermatology for consideration of oral isotretinoin may be warranted

For post-inflammatory hyperpigmentation, management includes:

• Sun protection: Daily broad-spectrum SPF 30+ sunscreen to prevent darkening of pigmented areas

• Topical treatments: Prescription treatments containing ingredients such as azelaic acid may help fade hyperpigmentation. More potent agents like hydroquinone are prescription-only and typically used under dermatology supervision

• Patience: Post-inflammatory pigmentation typically improves gradually over 6-12 months with appropriate management

Monitoring and follow-up are essential components of safe testosterone therapy. UK guidelines recommend baseline tests followed by review at 3 months and then 6-12 monthly once stable. Regular monitoring should include testosterone levels, haematocrit (with treatment paused if ≥0.54), and prostate-specific antigen (PSA) in men over 40 or at higher risk. Any persistent or concerning skin changes should be documented and investigated appropriately, with dermatology referral considered for complex cases. Patients should be reassured that most skin side effects are manageable and do not necessarily require treatment discontinuation.

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