Many people wonder whether using Testogel alongside an HRT patch will cause problems or affect how their hormones work. Testogel is a testosterone gel licensed for male hypogonadism, whilst HRT patches typically contain oestrogen for menopausal symptoms or gender-affirming care. In certain clinical situations—such as treating low sexual desire in postmenopausal women or managing complex endocrine conditions—both treatments may be used together under specialist supervision. Understanding how these hormones interact, the safety considerations involved, and when specialist oversight is essential can help you make informed decisions about your hormone therapy.

Understanding Testogel and HRT Patches

Testogel and HRT (hormone replacement therapy) patches are both forms of hormone therapy that serve different purposes and contain different hormones. Testogel is a testosterone gel applied to the skin, licensed in the UK specifically for adult male hypogonadism (low testosterone levels). The gel delivers testosterone transdermally, meaning it is absorbed through the skin into the bloodstream.

HRT patches typically contain oestrogen (with or without progestogen) and are most commonly prescribed for women experiencing menopausal symptoms or as part of gender-affirming care for transgender women. These patches deliver hormones steadily through the skin over several days, helping to alleviate symptoms such as hot flushes, night sweats, mood changes, and vaginal dryness. Women with a uterus who use systemic oestrogen therapy also require a progestogen to protect the endometrium.

While testosterone and oestrogen have different physiological effects, they are not always opposing. In UK menopause care, adding low-dose testosterone to oestrogen HRT is a recognised option for women with persistent low sexual desire despite adequate oestrogen therapy, though this use of testosterone is off-label. The British Menopause Society and NICE guidance (NG23) acknowledge this practice, which requires specialist oversight and informed consent.

Other clinical scenarios where both hormones might be used include certain endocrine disorders or during transitional phases of gender-affirming care under specialist supervision. It's important to note that Testogel is not licensed for women or for gender-affirming care in the UK.

If you have been prescribed both treatments, or are considering using them together, it is crucial to have this managed by a healthcare professional with expertise in endocrinology, menopause medicine, or gender healthcare, as the combination requires careful monitoring and individualised treatment planning.

How Testogel and HRT Patches Work in the Body

Testogel works by supplementing the body's testosterone levels. Once applied to clean, dry skin (usually on the shoulders, upper arms, or abdomen), the testosterone is absorbed through the skin and enters the bloodstream. Testosterone is an androgen hormone responsible for developing and maintaining male secondary sexual characteristics, including muscle mass, bone density, body hair growth, deepening of the voice, and libido. It also plays important roles in mood regulation, energy levels, and metabolic function. The gel formulation allows for steady absorption, typically reaching therapeutic levels within a few hours and maintaining them with daily application.

The pharmacokinetics of Testogel involve conversion of some testosterone to its active metabolite dihydrotestosterone (DHT) and to oestradiol via the enzyme aromatase. This means that some testosterone is naturally converted to oestrogen in the body—a normal physiological process that occurs in both men and women, though to different degrees.

HRT patches containing oestrogen work by delivering oestradiol (the primary form of oestrogen) directly through the skin into the bloodstream, bypassing first-pass metabolism in the liver. This transdermal delivery method provides more stable hormone levels compared to oral preparations and is associated with a lower risk of venous thromboembolism (blood clots) compared to oral oestrogen. According to NICE guidance, transdermal oestrogen is the preferred option for women with increased risk factors for blood clots. Oestrogen acts on oestrogen receptors throughout the body, affecting the reproductive system, bones, cardiovascular system, skin, and brain.

When oestrogen and testosterone are both present in the body, their effects depend on the doses used and the individual's physiology. At physiological female doses, testosterone can complement oestrogen's effects on sexual function, energy and mood, while at higher doses, testosterone promotes male characteristics and anabolic effects. The balance between these hormones requires careful clinical consideration.

It's important to note that testosterone is contraindicated in pregnancy and can cause harm to a developing foetus. If you could become pregnant, effective contraception is essential when using testosterone.

Potential Interactions Between Testogel and HRT Patches

When considering the concurrent use of Testogel and oestrogen-containing HRT patches, it's important to understand that there is no specific pharmacokinetic interaction listed in standard drug interaction databases. The clinical considerations relate primarily to overlapping effects and maintaining appropriate hormone levels for your specific situation.

In postmenopausal women, adding low-dose testosterone to oestrogen HRT is an evidence-based, off-label option for low sexual desire disorder when HRT alone is insufficient, as recognised by NICE and the British Menopause Society. In this context, the goal is to maintain testosterone within the female reference range while avoiding androgenic side effects.

At physiological doses appropriate for women, the amount of oestrogen produced through aromatisation of testosterone is generally not clinically significant when added to HRT. However, at higher doses (such as those used for male replacement therapy), more testosterone may convert to oestrogen, potentially affecting the overall hormonal balance.

The effects of testosterone and oestrogen are dose-dependent and context-specific rather than simply antagonistic. In some tissues, they may have complementary effects (such as on bone density and sexual function), while in others, their effects may differ. The key is appropriate dosing and monitoring for your specific clinical situation.

For individuals using both treatments for gender-affirming care or complex endocrine conditions, the balance between these hormones requires specialist oversight. The doses used and the desired effects will determine the appropriate monitoring and management approach.

While the combination has been studied in specific contexts (such as for female sexual dysfunction), long-term safety data on combined use remain limited, particularly at higher doses. This underscores the importance of specialist supervision, regular monitoring, and individualised treatment planning.

Safety Considerations When Using Both Treatments

If you are using both Testogel and an HRT patch, several important safety considerations must be kept in mind. Regular monitoring is essential and typically includes:

• Testosterone levels (aiming to keep within the appropriate range for your treatment goals)

• Haematocrit (red blood cell concentration) at baseline, 3-6 months, and then annually, as testosterone can increase red blood cell production

• Blood pressure checks

• Cardiovascular risk assessment and lipid profile as appropriate

• For men using testosterone replacement therapy, PSA (prostate-specific antigen) monitoring per local protocol

Cardiovascular health is another key consideration. Transdermal oestrogen is associated with a lower risk of venous thromboembolism than oral oestrogen and is preferred for those with higher cardiovascular risk factors. The combination of both hormones should be carefully considered in individuals with existing cardiovascular disease.

Application site management is important for both medications:

• Apply Testogel to clean, dry skin, allow it to dry completely, and then cover the area with clothing

• Wash your hands thoroughly after application

• Apply the HRT patch to a different area from the Testogel

• Avoid washing the application site for the period recommended in the product information

• Take precautions to prevent transfer of testosterone to others, especially children and pregnant women, through skin-to-skin contact

Adverse effects to watch for include:

• Androgenic effects: acne, increased facial/body hair, scalp hair thinning, voice deepening (which may be irreversible), and clitoromegaly in women

• Mood changes or irritability

• Breast tenderness or changes

• Signs of fluid retention (swelling of ankles or hands)

• Skin reactions at application sites

Emergency warning signs requiring immediate medical attention include:

• Chest pain, pressure, or tightness (call 999)

• Sudden severe headache, facial weakness, arm weakness, difficulty speaking (possible stroke symptoms - call 999)

• Sudden unexplained breathlessness (call 999)

• Severe leg pain or swelling, especially if one-sided (call 111 or see urgent care)

If you experience any suspected side effects, you can report them through the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk.

When to Speak to Your GP or Specialist

You should speak to your GP or specialist before starting both Testogel and an HRT patch concurrently, or if you are already using one and are considering adding the other. This combination requires specialist oversight—ideally from an endocrinologist, menopause specialist, or gender identity clinic, depending on the reason for your treatment. Self-medicating or combining these treatments without medical supervision is not advisable due to the complex hormonal interactions and potential health risks involved.

Contact your healthcare provider promptly if you experience any of the following whilst using both treatments:

• Emergency situations (call 999 immediately):
• Chest pain, pressure or tightness (possible heart attack)
• Sudden severe headache, facial drooping, arm weakness, speech difficulties (possible stroke)

• Sudden unexplained breathlessness (possible pulmonary embolism)

• Urgent concerns (call 111 or seek urgent care):

• Painful, swollen, warm leg (possible deep vein thrombosis)

• Significant mood changes: severe depression, anxiety, or emotional instability

• Routine review needed:

• Androgenic side effects: acne, increased facial/body hair, scalp hair thinning, voice changes
• Unscheduled vaginal bleeding that persists beyond 6 months after starting or changing HRT, becomes heavy, or occurs after a period of no bleeding
• Significant weight gain or fluid retention
• Skin reactions at application sites
• Signs of liver problems: yellowing of skin or eyes (jaundice), dark urine, persistent nausea, or abdominal pain

Your healthcare provider will need to conduct regular reviews—typically at 3 months after starting treatment, then annually once stable—to assess your response to treatment, monitor for adverse effects, and adjust dosages as needed. For women using testosterone, clinicians aim to keep serum testosterone within the female reference range to minimise side effects while achieving benefits.

If you have a uterus and are using systemic oestrogen therapy, you will also need a progestogen to protect the endometrium, unless you have had a hysterectomy.

If you have been prescribed these medications by different healthcare providers who may not be aware of each other's prescriptions, it is essential to inform both of them immediately so that your care can be coordinated appropriately. Your pharmacist can also provide valuable advice and may identify potential issues when dispensing your medications.

Frequently Asked Questions