Is Testogel made from plants? Whilst the active ingredient testosterone in Testogel is synthetically manufactured in pharmaceutical laboratories, the starting materials often originate from plant-derived steroid precursors such as diosgenin from wild yam or stigmasterol from soya beans. These compounds undergo multiple chemical transformation steps under stringent Good Manufacturing Practice standards to produce bioidentical testosterone—structurally identical to the hormone your body produces naturally. This article explains Testogel's manufacturing process, ingredient composition, and suitability for vegetarians and vegans, alongside essential safety information for patients prescribed this testosterone replacement therapy in the UK.
Summary: Testogel contains synthetically manufactured testosterone derived from plant-based steroid precursors such as diosgenin or stigmasterol, which undergo chemical transformation to produce bioidentical testosterone identical to human hormone.
- Testogel is a transdermal testosterone replacement therapy gel licensed in the UK for treating male hypogonadism confirmed by clinical symptoms and consistently low morning testosterone levels measured twice.
- The active ingredient testosterone is synthesised from plant-derived compounds (wild yam or soya beans) through multiple chemical steps under Good Manufacturing Practice standards, not extracted directly from plants or animals.
- Bioidentical testosterone in Testogel is structurally identical to endogenous human testosterone and metabolised through the same enzymatic pathways as naturally produced hormone.
- Regular monitoring is essential including testosterone levels, full blood count, haematocrit, prostate-specific antigen, and blood pressure at baseline, 3 months, 6 months, 12 months, then annually.
- Critical safety precautions include avoiding skin-to-skin contact with others (especially pregnant women and children) until application site is washed, allowing gel to dry completely, and avoiding bathing for at least 2 hours post-application.
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What Is Testogel and How Is It Manufactured?
Testogel is a transdermal testosterone replacement therapy (TRT) gel licensed in the UK for treating male hypogonadism—a condition characterised by abnormally low testosterone levels confirmed by clinical symptoms and consistently low morning total testosterone measurements on two separate occasions. The gel is applied once daily to clean, dry, intact skin where testosterone is absorbed directly into the bloodstream, bypassing first-pass hepatic metabolism.
In the UK, Testogel is available in two formulations: Testogel 50 mg gel in sachets (1% strength, delivering 10 mg testosterone per gram) and Testogel 16.2 mg/g gel in a metered-dose pump (each pump actuation dispenses 1.25 g gel containing 20.25 mg testosterone). Application sites differ by formulation: the 1% sachet may be applied to shoulders, upper arms, or abdomen, whilst the 16.2 mg/g pump should be applied only to shoulders and upper arms. The gel must not be applied to the genital area.
The active pharmaceutical ingredient in Testogel is testosterone, which is manufactured synthetically in pharmaceutical laboratories rather than extracted from animal or plant sources. Modern pharmaceutical-grade testosterone is typically produced through chemical synthesis starting from plant-derived steroid precursors, most commonly diosgenin or stigmasterol. These compounds are extracted from plants such as wild yam (Dioscorea species) or soya beans, then undergo multiple chemical transformation steps in controlled laboratory conditions to yield bioidentical testosterone. However, precise manufacturing sources and processes may vary by manufacturer and over time.
This synthetic manufacturing process ensures consistent purity, potency, and quality control—critical factors for a prescription medicine. The testosterone molecule produced is structurally identical to endogenous human testosterone (hence termed 'bioidentical'), meaning the body metabolises it through exactly the same enzymatic pathways as naturally produced hormone. The synthesis involves complex organic chemistry performed under stringent Good Manufacturing Practice (GMP) standards as required by the Medicines and Healthcare products Regulatory Agency (MHRA) and European Medicines Agency (EMA).
Whilst the starting materials may originate from plants, the final testosterone molecule in Testogel is a synthetic pharmaceutical product rather than a simple plant extract. This distinction is important for understanding both the manufacturing process and the product's suitability for different dietary preferences.
Important administration precautions must be followed: wash hands thoroughly with soap and water immediately after application; allow the gel to dry completely before dressing (approximately 3–5 minutes); cover the application site with clothing; avoid bathing, showering, or swimming for at least 2 hours after application; keep away from naked flames and do not smoke until the gel has dried, as it is flammable; and avoid skin-to-skin contact with others (especially pregnant women and children) until the site has been washed. If contact occurs, the other person should wash the affected area immediately with soap and water.
Active and Inactive Ingredients in Testogel
The active ingredient in Testogel is testosterone. The UK formulations are:
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Testogel 50 mg gel in sachets: Each 5 g sachet contains 50 mg testosterone (1% strength, or 10 mg per gram). The usual starting dose is one sachet applied once daily.
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Testogel 16.2 mg/g gel (metered-dose pump): Each pump actuation dispenses 1.25 g gel containing 20.25 mg testosterone. The usual starting dose is two pump actuations (40.5 mg testosterone) applied once daily.
Doses are adjusted according to individual patient requirements and serum testosterone monitoring, as directed by the prescribing clinician. It is important to note that other testosterone gel brands available in the UK (such as Tostran 2% and Testavan 2%) are different products with different strengths and are not interchangeable with Testogel.
In addition to testosterone, Testogel contains several inactive ingredients (excipients) that serve important pharmaceutical functions:
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Ethanol (alcohol): Acts as a solvent and penetration enhancer, facilitating testosterone absorption through the skin. The alcohol evaporates after application, leaving testosterone on the skin surface for gradual absorption.
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Carbomer: A synthetic polymer that provides the gel's characteristic consistency and helps maintain even distribution of testosterone throughout the formulation.
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Isopropyl myristate: An emollient that enhances skin penetration and improves the gel's spreading properties.
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Purified water: Serves as the aqueous phase of the gel formulation.
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Sodium hydroxide: Used to adjust the pH to optimal levels for skin compatibility and stability.
The carbomer is a synthetic acrylic acid polymer. However, the precise origin of all excipients (for example, whether isopropyl myristate or other components are derived from plant or synthetic sources) can vary by manufacturer and batch. Patients requiring confirmation of vegan, vegetarian, halal, or kosher suitability should contact the Marketing Authorisation Holder directly or consult their pharmacist, as manufacturing processes and ingredient sources may change.
Patients with specific allergies or sensitivities should review the complete ingredient list in the patient information leaflet supplied with their specific Testogel presentation. The MHRA-approved Summary of Product Characteristics (SmPC) available via the electronic Medicines Compendium (eMC) provides comprehensive ingredient information for healthcare professionals.
Synthetic vs Natural Testosterone: Understanding the Difference
The term 'natural testosterone' can be misleading in pharmaceutical contexts. Whilst testosterone itself is a naturally occurring hormone produced primarily in the testes (and in smaller amounts in the adrenal glands and ovaries), the testosterone used in medications like Testogel is synthetically manufactured in laboratories. However, this synthetic testosterone is bioidentical—meaning its molecular structure is absolutely identical to the testosterone your body produces naturally.
This contrasts with some older forms of hormone therapy that used non-bioidentical or semi-synthetic hormones with slightly altered molecular structures (such as methyltestosterone), which may have different pharmacological properties and side-effect profiles. Bioidentical testosterone is metabolised by the body through exactly the same enzymatic pathways as endogenous testosterone, converting to dihydrotestosterone (DHT) via 5α-reductase and to oestradiol via aromatase.
Historically, testosterone for medical use was extracted from animal sources, but this practice has been obsolete for decades due to concerns about purity, consistency, disease transmission risk, and ethical considerations. Modern synthesis from plant steroid precursors offers several advantages:
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Pharmaceutical purity: Synthetic processes can achieve >99% purity with minimal contaminants.
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Consistent potency: Each batch contains precisely controlled testosterone concentrations.
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Regulatory compliance: Manufacturing meets stringent MHRA and European Medicines Agency (EMA) standards.
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Scalability: Synthetic production can meet global demand reliably.
From a clinical perspective, the molecular identity of testosterone synthesised from plant precursors is identical to the hormone your body produces naturally—the body cannot distinguish between the two at a molecular level. However, it is important to understand that the safety and efficacy of testosterone replacement therapy depend on the dose, route of administration, and individual patient factors, not on the origin of the precursor materials used in synthesis.
Testosterone replacement therapy carries recognised risks that require careful monitoring, including:
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Erythrocytosis (increased red blood cell production): Can increase risk of blood clots.
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Skin reactions: Acne, oily skin, or application-site reactions.
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Gynaecomastia: Breast tissue enlargement due to conversion of testosterone to oestradiol.
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Blood pressure increases: Requiring monitoring and management.
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Potential exacerbation of sleep apnoea: Particularly in at-risk individuals.
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Reduced fertility: TRT can suppress sperm production and should not be used by men actively trying to conceive.
Regular monitoring and clinical review are essential to balance the benefits of symptom relief against these potential risks, as detailed in NICE Clinical Knowledge Summaries and the Testogel Summary of Product Characteristics.
Safety and Suitability for Vegetarians and Vegans
Testogel may be suitable for vegetarians and vegans from an ingredient perspective, as the active testosterone is synthesised from plant-derived steroid precursors and the listed excipients do not include obvious animal-derived ingredients such as gelatin or lactose. However, the precise origin of all excipients and any processing aids used during manufacture can vary and are not always disclosed in public documentation. Patients following strict vegan principles, or those requiring halal or kosher certification, should contact the Marketing Authorisation Holder directly to confirm suitability, as formal certification is not routinely provided.
For patients with specific dietary, religious, or ethical requirements, the following points are relevant:
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Alcohol content: Testogel contains ethanol, which evaporates after application. This may be a consideration for some individuals with religious or personal objections to alcohol, though topical application differs significantly from consumption.
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Allergy considerations: The synthetic nature of ingredients means there is no risk of animal protein allergies, but sensitivity to synthetic excipients (such as carbomer or isopropyl myristate) remains possible.
From a clinical safety perspective, Testogel's suitability depends primarily on medical factors. Testosterone replacement therapy should only be initiated in men with clinical features of hypogonadism (such as reduced libido, erectile dysfunction, fatigue, reduced muscle mass, or mood changes) and consistently low morning total testosterone levels measured on two separate occasions, after appropriate evaluation including luteinising hormone (LH), follicle-stimulating hormone (FSH), and prolactin. Low testosterone with low or normal LH/FSH may suggest pituitary disease and requires specialist referral.
Contraindications include prostate cancer, male breast cancer, and caution is required in cardiovascular disease, sleep apnoea, polycythaemia, or severe heart failure. Regular monitoring is essential and should include:
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Testosterone levels: Timing of blood sampling is product-specific. For Testogel 16.2 mg/g pump, measure 2–4 hours after application; for Testogel 1% sachets, measure pre-dose in the morning. Check at 3 months, 6 months, 12 months, then annually, with dose adjustment as needed.
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Full blood count (FBC) and haematocrit: Check at baseline, 3 months, 6 months, 12 months, then annually. If haematocrit exceeds 54%, withhold or reduce the dose and investigate the cause.
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Prostate-specific antigen (PSA) and digital rectal examination (DRE): As indicated by age and risk factors (typically men aged over 50 years or those with risk factors for prostate cancer). A rising PSA or abnormal DRE requires urological referral.
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Blood pressure: Monitor regularly, as testosterone can increase blood pressure.
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Fertility counselling: TRT suppresses spermatogenesis and can reduce or stop sperm production. Men wishing to father children should discuss alternative treatments or sperm banking before starting therapy.
Patients should contact their GP or seek urgent medical attention if they experience:
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Signs of excessive testosterone: severe acne, aggression, mood disturbance, or sleep disturbance.
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Symptoms suggesting a blood clot (venous thromboembolism): leg pain, swelling, or redness; chest pain; breathlessness.
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Symptoms suggesting myocardial infarction or stroke: chest pain, sudden weakness, speech difficulty, or facial drooping.
Critical transference precautions must be observed: the gel must be applied to areas that will be covered by clothing to prevent transfer to partners or children through skin-to-skin contact. Wash hands thoroughly with soap and water immediately after application. If another person (especially a pregnant woman or child) comes into contact with the application site, they should wash the affected area with soap and water immediately. Avoid skin-to-skin contact until the application site has been washed. Allow the gel to dry completely before dressing, avoid bathing or swimming for at least 2 hours after application, and keep away from naked flames or smoking until dry, as the gel is flammable.
Patients are advised to report any suspected adverse effects via the MHRA Yellow Card scheme (available at yellowcard.mhra.gov.uk or via the Yellow Card app). Comprehensive guidance on testosterone replacement therapy, including diagnosis, monitoring, and referral pathways, is available in the NICE Clinical Knowledge Summaries on testosterone deficiency in adult men and the Summary of Product Characteristics for Testogel available via the electronic Medicines Compendium (eMC).
Frequently Asked Questions
Can vegetarians and vegans use Testogel?
Testogel may be suitable for vegetarians and vegans as the testosterone is synthesised from plant-derived precursors and listed excipients do not include obvious animal-derived ingredients. However, patients following strict vegan principles or requiring halal or kosher certification should contact the Marketing Authorisation Holder directly to confirm suitability, as precise excipient origins and processing aids may vary.
What is bioidentical testosterone in Testogel?
Bioidentical testosterone means the molecular structure is absolutely identical to the testosterone your body produces naturally. The body metabolises it through exactly the same enzymatic pathways as endogenous testosterone, converting to dihydrotestosterone via 5α-reductase and to oestradiol via aromatase.
What monitoring is required when using Testogel?
Regular monitoring includes testosterone levels (at 3, 6, 12 months then annually), full blood count and haematocrit (same schedule), prostate-specific antigen and digital rectal examination as indicated by age and risk factors, and blood pressure monitoring. If haematocrit exceeds 54%, the dose should be withheld or reduced and the cause investigated.
The health-related content published on this site is based on credible scientific sources and is periodically reviewed to ensure accuracy and relevance. Although we aim to reflect the most current medical knowledge, the material is meant for general education and awareness only.
The information on this site is not a substitute for professional medical advice. For any health concerns, please speak with a qualified medical professional. By using this information, you acknowledge responsibility for any decisions made and understand we are not liable for any consequences that may result.
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