Testogel (testosterone gel) is a transdermal hormone replacement therapy used to treat confirmed hypogonadism in men. Proper application technique is essential to ensure optimal absorption through the skin and achieve therapeutic testosterone levels. Many factors—including application timing, skin condition, and post-application care—can significantly influence how much testosterone enters the bloodstream. Understanding these variables and avoiding common mistakes helps maximise treatment effectiveness whilst minimising the risk of transferring testosterone to others. This article provides evidence-based guidance aligned with MHRA-approved product information to help patients optimise Testogel absorption and achieve better clinical outcomes.

How Testogel Is Absorbed Through the Skin

Testogel (testosterone gel) is a transdermal preparation designed to deliver testosterone through the skin directly into the bloodstream. The active ingredient, testosterone, is formulated in an alcohol-based gel that facilitates absorption through the stratum corneum—the outermost layer of the skin. Once applied, the alcohol evaporates quickly, leaving testosterone on the skin surface where it gradually penetrates through the epidermis and dermis into the capillary network beneath.

The absorption process relies on passive diffusion, meaning testosterone molecules move from an area of high concentration (the skin surface) to lower concentration (the bloodstream). This process typically takes several hours, with peak serum testosterone levels generally achieved within a few hours after application, though absorption continues over the dosing interval. The proportion of applied testosterone that reaches the bloodstream varies by formulation and individual factors, which is why the gel contains a higher concentration than the amount needed in circulation.

Key factors influencing transdermal absorption include:

• Skin thickness and condition – thinner, intact skin absorbs medication more readily

• Blood flow to the application area – increased circulation enhances absorption

• Skin hydration – well-hydrated skin generally permits better penetration

• Skin contact – dense body hair can impede direct contact between gel and skin

Understanding this mechanism is essential for optimising treatment outcomes. The MHRA-approved Summary of Product Characteristics (SmPC) and Patient Information Leaflet (PIL) emphasise that proper application technique significantly impacts the amount of testosterone that reaches systemic circulation, making patient education a cornerstone of effective testosterone replacement therapy.

Proper Application Technique for Maximum Absorption

Correct application technique is fundamental to ensuring optimal absorption of Testogel. The manufacturer's instructions, as detailed in the MHRA-approved SmPC and PIL, provide specific guidance that should be followed meticulously to achieve therapeutic testosterone levels.

Step-by-step application process:

Begin by ensuring the application site is clean, dry, and intact. Wash your hands thoroughly before opening the sachet or pump. Apply Testogel to the shoulders and upper arms (and abdomen for some formulations) as directed by your prescriber—these areas provide consistent absorption rates. Do not apply to the genital area, as this can cause local irritation and is not an approved application site. Tear open the sachet completely or dispense the prescribed number of pump actuations, then spread the gel thinly and evenly over a large surface area of the designated site using your fingers or palm.

The gel should be applied in a thin, uniform layer and spread gently. A light spreading motion is sufficient—the gel will absorb naturally without vigorous rubbing. After application, allow the gel to dry completely for 3 to 5 minutes before dressing. This drying time is crucial as it allows the alcohol carrier to evaporate, leaving testosterone on the skin surface ready for absorption. The gel is flammable until dry—avoid naked flames and do not smoke until the gel has dried completely.

Important post-application measures:

• Wash your hands immediately and thoroughly with soap and water after application to prevent accidental transfer

• Wait at least 2 hours (for Testogel 16.2 mg/g) before showering, bathing, or swimming; check your specific product instructions as timing may vary by formulation

• Cover the application site with clothing once dry to minimise transfer to others

• Wash the application site with soap and water before situations where direct skin-to-skin contact is anticipated (e.g., intimate contact)

• Avoid close skin contact with pregnant women and children; if unintended contact occurs, wash the exposed area with soap and water as soon as possible

• Do not apply occlusive dressings or expose the application site to external heat sources (e.g., hot water bottles, heating pads), as these can alter absorption

Following these steps consistently ensures that the maximum amount of testosterone remains on your skin for absorption rather than being washed away, rubbed off, or transferred to others.

Factors That Affect Testogel Absorption

Multiple physiological and environmental factors can influence how effectively Testogel is absorbed, potentially affecting treatment outcomes and serum testosterone levels.

Skin-related factors play a primary role in absorption variability. Skin thickness varies across different body areas, with thinner skin generally permitting greater absorption. The presence of skin conditions such as eczema, psoriasis, or dermatitis can compromise the skin barrier, potentially altering absorption rates unpredictably. Do not apply Testogel to broken, irritated, or damaged skin. Conversely, thickened or scarred skin may reduce penetration. Age-related changes in skin structure may affect absorption, though no specific dose adjustment based solely on age is routinely required.

Physical activity and perspiration can impact absorption. Excessive sweating within the first few hours after application can wash away testosterone before it fully penetrates the skin. Vigorous exercise shortly after application may increase perspiration, which can reduce the amount of testosterone absorbed. Plan application times when physical exertion is minimal for several hours.

Environmental temperature and humidity influence both the drying time of the gel and skin hydration status. Very hot conditions may increase sweating, potentially reducing absorption, whilst cold environments might slow the absorption process due to reduced skin blood flow. Maintaining proper application technique remains the most important factor.

Body composition and application site selection also matter. The presence of dense body hair can interfere with direct skin contact, potentially reducing absorption—this is why shoulders and upper arms are preferred sites for most formulations.

Concurrent use of skincare products such as moisturisers, sunscreens, or other topical medications can create a barrier that impedes testosterone absorption. As per the product information, apply Testogel to clean skin without other products, or allow several hours between applications of different topical treatments if needed.

Common Mistakes That Reduce Absorption

Several frequently encountered errors can substantially diminish Testogel absorption, leading to suboptimal testosterone levels and potentially inadequate symptom control. Recognising and avoiding these mistakes is essential for treatment success.

Premature washing or swimming represents one of the most significant errors. For Testogel 16.2 mg/g, showering, bathing, or swimming should be avoided for at least 2 hours after application. Different formulations may have different recommended intervals, so always check your specific product instructions. Washing too soon removes testosterone that has not yet been absorbed. Patients who exercise regularly or have occupations involving water exposure should plan application times accordingly.

Applying to damp or wet skin prevents proper gel adhesion and dilutes the testosterone concentration on the skin surface. Always ensure the application site is completely dry before applying Testogel. If applying after showering, wait until skin is thoroughly dry.

Spreading the gel incorrectly can reduce absorption. Testogel should be spread gently and thinly over a large surface area of the approved application site(s). Avoid vigorous rubbing or massage. A light spreading motion allows the gel to remain on the skin surface for optimal absorption.

Inconsistent application sites can lead to variable absorption rates. Use only the approved sites specified in your product information (typically shoulders and upper arms, and abdomen for some formulations). Avoid unapproved areas such as the scrotum, which can cause irritation, or areas with broken or irritated skin.

Covering the application site too quickly before the gel has dried prevents proper evaporation of the alcohol carrier and poses a fire risk. Clothing should only be applied after the gel appears completely dry to touch, typically 3 to 5 minutes after application.

Applying other topical products immediately before or after Testogel can create barriers to absorption. Moisturisers, sunscreens, and other skincare products should be applied at different times of day, ideally with several hours' separation.

Failing to prevent transfer to others is both a safety concern and can reduce the dose you absorb. Always cover the application site with clothing once dry. Wash the application site with soap and water before anticipated close skin contact. If unintended skin-to-skin contact occurs (especially with pregnant women or children), wash the contact area with soap and water as soon as possible.

If you suspect absorption issues due to any of these mistakes, contact your GP or endocrinologist. They may arrange blood tests to check your testosterone levels and adjust your treatment regimen accordingly.

When to Apply Testogel for Best Results

The timing of Testogel application can influence both absorption efficiency and how well the treatment aligns with your body's natural hormonal rhythms, though flexibility exists to accommodate individual lifestyles.

Morning application is generally recommended for several physiological and practical reasons. Testosterone levels in healthy males naturally peak in the early morning and decline throughout the day. Applying Testogel in the morning helps replicate this circadian pattern, potentially providing more physiological testosterone replacement. Additionally, morning application allows the crucial interval before washing (at least 2 hours for Testogel 16.2 mg/g; check your specific product) to elapse during waking hours, making it easier to avoid premature water exposure.

Optimal timing considerations include:

• After morning shower – applying to clean, dry skin after your morning wash ensures the application site is free from other products and allows time for absorption before evening bathing

• Before dressing for the day – this timing ensures the gel dries before clothing contact and minimises transfer risk to others during the day

• When physical activity is minimal – avoid applying immediately before exercise, heavy physical labour, or situations likely to cause significant perspiration

• Consistent daily timing – applying at approximately the same time each day helps maintain stable testosterone levels and establishes a routine that improves adherence

Special circumstances may require timing adjustments. If you work shifts or have an irregular schedule, discuss the best application time with your prescriber to ensure it fits your routine whilst allowing adequate time before washing and minimising transfer risk. If you swim regularly, apply Testogel at least 2 hours (or longer, depending on your formulation) before entering the water, or schedule swimming for the following day.

If you miss a dose, apply it as soon as you remember on the same day, then return to your regular schedule the next day. Do not apply a double dose to compensate. If you frequently forget doses, consider setting a daily alarm or linking application to an established morning routine such as breakfast or teeth brushing.

Patients experiencing inadequate symptom control despite proper application should contact their GP or specialist. Blood tests measuring serum testosterone levels can determine whether absorption is adequate or whether dose adjustment is needed. UK guidance recommends monitoring testosterone levels periodically during treatment (typically measured a few hours after application for gel formulations) to ensure therapeutic targets are achieved. Monitoring also includes full blood count to check haematocrit levels (your prescriber may consider dose adjustment or interruption if haematocrit rises above 0.54) and prostate assessment where appropriate. Testosterone therapy should only be used in men with confirmed hypogonadism, and treatment should be reviewed periodically. Evidence on cardiovascular risk with testosterone therapy has been inconsistent; your prescriber will assess your individual risk and monitor you accordingly.

If you experience any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in the package leaflet. You can also report side effects directly via the Yellow Card Scheme at www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.

Frequently Asked Questions