TRT Gel vs. Injection: Which Form Is Right for You?

When deciding on testosterone replacement therapy (TRT), a practical question arises: gel or injection? Both delivery methods are approved by Swissmedic, both achieve therapeutic testosterone levels, and both are covered by mandatory health insurance. Yet they differ substantially in handling, pharmacokinetics, everyday practicality, and personal comfort. This guide compares the two main options on an evidence basis and helps you make the right choice together with your physician.

Testosterone Gel: Daily Application, Stable Levels

Testosterone gel (e.g. Testogel®, Androgel®) is applied once daily to the skin — typically on the upper arms, shoulders, or abdomen. The testosterone is absorbed through the skin and enters the bloodstream directly.

Advantages of Gel

Physiologically stable levels: The gel mimics the natural circadian rhythm. The TRAVERSE study, the largest randomised TRT trial with over 5,000 participants, used 1.62% testosterone gel and confirmed both efficacy and cardiovascular safety over a period of up to four years (Lincoff et al., 2023). Testosterone levels remain relatively constant throughout the day — without the peaks and troughs that can occur with injections.

Pain-free application: No needle, no injection pain. For men with needle anxiety or those who prefer a non-invasive option, the gel is the more comfortable choice.

Flexible dose adjustment: The dose can be adjusted in small increments — an advantage over injections, where dosing occurs in larger steps. If side effects appear, the dose can be reduced more quickly.

Rapid reversibility: When the gel is discontinued, exogenous testosterone levels normalise within a few days. This can be relevant if side effects occur or therapy needs to be interrupted.

Disadvantages of Gel

Daily routine: The gel must be applied at the same time every day. Missed applications lead to level drops. For men who prefer a "set-and-forget" solution, this can be inconvenient.

Transfer risk: Until the gel has fully absorbed (approximately 2–5 hours), there is a risk of transferring testosterone to those in close contact — particularly female partners and children. Skin contact should be avoided during this time or covered clothing worn. The Endocrine Society recommends covering the application site after drying (Bhasin et al., 2018).

Absorption varies: Skin permeability differs between individuals and can be influenced by sweating, bathing, or skincare products. Some men do not achieve desired levels despite correct application.

Testosterone Injections: Less Frequent, Stronger Effect

Injections deliver testosterone directly into the muscle (intramuscular) or under the skin (subcutaneous). In Switzerland, two main variants are available: testosterone enanthate (e.g. Testoviron®), administered every 1–2 weeks, and testosterone undecanoate (Nebido®), administered only every 10–14 weeks.

Advantages of Injection

Infrequent application: Depending on the preparation, only every 1–2 weeks (enanthate) or every 10–14 weeks (undecanoate). This means less daily effort and no daily routine.

No transfer risk: Unlike the gel, there is no risk of transfer to partners or children — an important advantage for families with small children.

Reliable absorption: Drug uptake with injections is more predictable than with topical application. Individual skin characteristics play no role.

Cost advantage: Testosterone enanthate injections are generally cheaper than gel preparations. When covered by insurance this matters less, but can be relevant for self-payers. Details on costs are available in our article about TRT costs in Switzerland.

Disadvantages of Injection

Hormonal fluctuations: With short-acting injections (enanthate), a peak occurs shortly after injection followed by a gradual decline until the next dose. Some men notice a decrease in energy and mood in the days before the next injection. Long-acting undecanoate (Nebido) substantially reduces these fluctuations.

Injection pain: Intramuscular injections can be uncomfortable, particularly with Nebido (4 ml oil volume). Subcutaneous injections with smaller needles are an increasingly popular alternative with comparable efficacy (Al-Futaisi et al., 2006).

Doctor visits or self-injection: Nebido is typically administered by a physician, while enanthate can be self-injected after instruction. Self-injection requires correct technique and hygiene.

Direct Comparison: Gel vs. Injection

| Criterion | Gel | Injection (Enanthate) | Injection (Undecanoate) |

|---|---|---|---| | Application | Daily | Every 1–2 weeks | Every 10–14 weeks | | Level stability | Very stable | Fluctuations possible | Stable | | Pain-free | ✅ | ❌ | ❌ | | Transfer risk | ⚠️ Yes | ✅ No | ✅ No | | Dose flexibility | High | Medium | Low | | Cost/month | ~CHF 80–120 | ~CHF 30–60 | ~CHF 40–80 | | Self-administration | ✅ | ✅ (after training) | ❌ (physician) | | TRAVERSE evidence | ✅ (study form) | Comparable | Comparable |

What Do Guidelines Recommend?

The Endocrine Society (2018) and the Society for Endocrinology (2022) express no clear preference for a specific delivery form. Both recommend making the choice individually based on patient preference, lifestyle, cost, and clinical response (Bhasin et al., 2018; Jayasena et al., 2022).

In practice, many physicians — including those at Swiss TRT — begin with the gel, as it enables the safest initial titration: the dose can be quickly adjusted, levels remain stable, and if side effects occur, therapy can be immediately interrupted. If the gel fails to achieve the desired level or the patient prefers less frequent application, a switch to injections is made.

During a telemedicine consultation, your physician can advise you individually on which form best suits your situation. The entire process — from blood draw through diagnosis to prescription — can be conveniently managed online.

Can You Switch Between Delivery Forms?

Yes, switching is possible at any time and common in practice. Typical reasons for switching from gel to injection include inadequate absorption despite correct application, the desire for less daily effort, or concerns about transfer risk. Conversely, some men switch from injection to gel if they find the level fluctuations between injections bothersome or develop a fear of needles.

Your treating physician will recalculate the dosage when switching and request a follow-up blood test after 4–6 weeks to ensure the target level is achieved. Detailed information about relevant laboratory values is available in our article on blood work for TRT.

Practical Tips for Daily Life

Regardless of the chosen delivery form, there are practical aspects that make daily therapy easier. Gel users should apply the preparation at the same time each day — ideally in the morning after showering, as the skin is then clean and dry. Avoid skin contact with your partner or children for at least 2 hours after application, and wash your hands thoroughly. For injections, a fixed schedule is recommended: enter injection dates in your calendar and rotate the injection site (thigh, gluteal muscle) to minimise tissue irritation. Both forms require regular blood checks — at Swiss TRT, this is ensured through a structured monitoring programme. Store your medication at room temperature and check the expiry date regularly. When travelling abroad, we recommend carrying a medical certificate confirming the medical necessity of carrying testosterone preparations.

FAQ

Is gel or injection more effective?

Both delivery forms are equally effective when the correct dose is chosen. The Endocrine Society and the Society for Endocrinology confirm that both gel and injections achieve therapeutic testosterone levels and equally improve hypogonadism symptoms. The difference lies not in efficacy but in pharmacokinetics, handling, and personal comfort. The TRAVERSE study — the largest TRT safety trial ever — was conducted with testosterone gel and confirmed significant improvement in sexual function, vitality, and quality of life.

Which delivery form has fewer side effects?

The side effects of TRT (polycythaemia, acne, mood changes) are dose-dependent and occur with both forms. The advantage of gel is that the dose can be adjusted more quickly and precisely when side effects arise. With injections — particularly short-acting ones — level fluctuations can lead to more pronounced mood swings in some men. Long-acting undecanoate (Nebido) has this disadvantage to a lesser degree. Regular blood monitoring is essential with all forms to optimally adjust the dose and detect side effects early.

Is testosterone gel safe for my partner?

Testosterone gel can be transferred through skin contact and cause virilisation symptoms in women (e.g. voice deepening, increased body hair). However, this risk is manageable: the application site should be covered with clothing after drying, and the site should be washed before close skin contact. If small children live in the household, guidelines recommend particular caution or alternatively switching to an injection form.

Does health insurance cover both forms?

Yes, for physician-diagnosed hypogonadism, both gel and injections are covered by the mandatory basic health insurance (OKP) — minus deductible and co-payment. There is no difference in reimbursement eligibility. Detailed information about health insurance coverage for TRT is available in our separate guide.

Further Reading

• TRT Costs in Switzerland
• What Blood Work Do I Need for TRT?
• TRT Side Effects and How to Manage Them