Does TRT Cause Hair Loss? DHT, Genetics, and What You Can Do

Hair loss is one of the biggest fears men have about starting TRT. It comes up in every forum, every clinic consultation, every group chat. "Will testosterone make me go bald?" The anxiety is real, and the misinformation is worse. Some men avoid treatment they genuinely need because they saw a Reddit thread about someone's hairline receding three weeks into their protocol. Others start TRT, notice a few hairs on their pillow, and panic.

Here is the truth: TRT does not cause hair loss in every man. It accelerates a process that was already written into your DNA. If you carry the genetic variants for androgenetic alopecia, increasing your androgen levels (whether through TRT or naturally) will speed up miniaturisation of susceptible follicles. If you do not carry those variants, you could run testosterone enanthate for decades and keep a full head of hair.

This article breaks down the mechanism, the genetics, which TRT delivery methods raise DHT the most, how to monitor your risk with bloodwork, and what actually works if you want to protect your hair while on testosterone therapy.

The short answer: it depends on your genetics, not your testosterone

Androgenetic alopecia (AGA), commonly called male pattern baldness, affects roughly 50% of men by age 50 and up to 80% by age 80 (Kische et al., 2017). It is the most common form of hair loss in men, and its progression is driven by two factors: androgens and genetic susceptibility.

The androgen that matters is not testosterone itself. It is dihydrotestosterone (DHT), a more potent metabolite produced when the enzyme 5-alpha reductase converts testosterone in tissues like the scalp, prostate, and skin. DHT binds to androgen receptors in hair follicles roughly five times more strongly than testosterone does. In genetically susceptible follicles, this binding triggers miniaturisation: the follicle gradually shrinks, produces thinner and shorter hairs, and eventually stops producing visible hair altogether.

Here is the part most men miss: DHT only damages follicles that are genetically programmed to respond to it. Men without the susceptibility genes can have high DHT and never lose a hair. The androgen receptor gene (AR), located on the X chromosome, contains a polymorphic CAG repeat sequence. Shorter CAG repeats produce receptors with higher transcriptional activity, meaning those follicles respond more aggressively to DHT (Sawaya & Shalita, 1998).

This is why two men on identical TRT protocols can have completely different outcomes. One keeps his hair; the other notices thinning within months. The testosterone did not "cause" the hair loss. It provided more substrate for 5-alpha reductase, which produced more DHT, which accelerated a genetically predetermined process.

How DHT actually causes hair loss

Understanding the mechanism helps you make better decisions about prevention. Here is what happens at the follicle level.

The enzyme 5-alpha reductase exists in two isoforms. Type I is found in sebaceous glands and skin; Type II is concentrated in hair follicles, the prostate, and genital tissue. Type II is the primary driver of scalp DHT production. When testosterone reaches the dermal papilla cells at the base of a hair follicle, Type II 5-alpha reductase converts it to DHT locally.

In genetically susceptible follicles (frontal scalp and crown, but not the sides and back), DHT binding triggers several changes (Tawanwongsri et al., 2025). The active growth phase of the hair cycle (anagen) gets progressively shorter: hairs that used to grow for 3 to 5 years now grow for months or weeks. The follicle physically shrinks, replacing thick, pigmented terminal hairs with thin, unpigmented vellus hairs that are barely visible. Chronic low-grade inflammation around the follicle contributes to fibrosis, which may eventually make the process irreversible. DHT also disrupts the Wnt/beta-catenin signalling pathways that maintain the hair cycle, shifting the balance toward regression and resting phases rather than active growth.

This does not happen overnight. AGA is a slow process that plays out over years or decades. On TRT, the timeline may compress because you are providing a consistent, elevated level of DHT substrate. But the pattern is the same: frontal recession, crown thinning, eventual coalescence. The sides and back of the head are spared because those follicles lack the androgen receptor sensitivity. This is why hair transplants work: relocated follicles retain their original genetic programming.

Can low testosterone cause hair loss too?

This is one of the most overlooked points in the TRT-and-hair-loss conversation. Yes, low testosterone itself can contribute to hair thinning, and it looks different from androgenetic alopecia.

Testosterone (and DHT) are required for normal hair growth in androgen-dependent areas: the beard, chest, axillary hair, and to some extent the scalp. Severe hypogonadism can result in diffuse hair thinning, reduced body hair, and sparse beard growth. This is a sign of androgen deficiency, not androgen excess.

A population-based study of 373 men published in JAMA Dermatology found no significant association between serum testosterone levels and the presence or severity of AGA (Kische et al., 2017). Interestingly, while one study of 109 men found that AGA patients had higher serum DHT than controls, the correlation between circulating DHT and actual hair loss severity was weak (Zhang et al., 2018). What matters more is local DHT activity at the follicle level, which serum measurements cannot capture.

What this means practically: starting TRT to treat genuine hypogonadism may actually improve hair quality in some men, particularly if their hair thinning was partly driven by deficiency rather than AGA. If your hair is falling out and your testosterone is 150 ng/dL, fixing the deficiency is unlikely to make it worse and may help. The men who see hair changes on TRT are almost always those who already carried the genetic susceptibility and were going to lose their hair regardless; testosterone just moved the timeline forward.

Does your TRT delivery method matter?

Yes, and the difference is larger than most men expect. Not all TRT protocols raise DHT equally, and this is where the choice between injections, creams, and gels becomes relevant to hair loss risk.

A meta-analysis by Borst et al. (2014) quantified the difference: transdermal testosterone (creams and gels) increased DHT by an average of 5.46 times baseline, while intramuscular injections increased DHT by only 2.20 times baseline. That is a 2.5-fold greater DHT elevation with topical application compared to injections.

The reason is anatomical. The skin is rich in 5-alpha reductase, particularly Type I. When testosterone is applied directly to the skin and absorbed through the dermal layer, a large proportion is converted to DHT during first-pass metabolism through the skin itself, before it even reaches systemic circulation. Intramuscular injections bypass this entirely: the testosterone enters the bloodstream from the muscle depot and is converted to DHT at a lower rate through systemic 5-alpha reductase activity.

For men concerned about hair loss on TRT, this has a clear practical implication: injectable testosterone enanthate or testosterone cypionate will produce less DHT than creams or gels at equivalent testosterone levels. If you are currently on a topical protocol and noticing hair changes, switching to injections may reduce your DHT exposure without changing your testosterone dose. Discuss this with your prescribing physician.

How to track your DHT with bloodwork

Most standard TRT blood panels do not include DHT. They check total and free testosterone, oestradiol, haematocrit, and sometimes SHBG. If you are concerned about hair loss, specifically request a DHT level.

Here is what to look for:

• Normal male DHT range: approximately 30 to 85 ng/dL (1.0 to 2.9 nmol/L), depending on the lab and assay method.
• On injectable TRT: expect DHT to roughly double from baseline. If your pre-TRT DHT was 40 ng/dL, you might see 70 to 90 ng/dL on injections.
• On transdermal TRT: expect DHT to increase 4 to 6 times baseline. The same man could see DHT of 160 to 240 ng/dL or higher on cream.

A single DHT reading does not predict hair loss. Local DHT activity at the follicle matters more than what shows up in your blood, and your genetic susceptibility determines whether elevated DHT translates to follicle damage. But tracking DHT over time gives you data. If your DHT is 3x baseline and your hairline is stable after 12 months, you are probably not highly susceptible. If your DHT is modestly elevated and you are shedding, genetics is doing the heavy lifting.

For a comprehensive guide to all the markers you should track on TRT, see our complete guide to bloodwork for bodybuilders.

Prevention strategies that actually work

If you are genetically susceptible and want to protect your hair while on TRT, you have several evidence-based options. None of them are perfect. All involve trade-offs.

Finasteride (1 mg daily)

Finasteride is a Type II 5-alpha reductase inhibitor. It blocks the enzyme responsible for converting testosterone to DHT in hair follicles and the prostate. At 1 mg daily, it reduces scalp DHT by approximately 64% and serum DHT by about 70% (Kaufman et al., 1998).

In the landmark two-year trial, 83% of men on finasteride maintained or increased hair count versus 28% on placebo. It is the most studied oral treatment for AGA and remains the first-line pharmaceutical option.

The trade-off: finasteride carries a risk of sexual side effects. A meta-analysis by Lee et al. (2019) found that 5-alpha reductase inhibitors were associated with higher rates of erectile dysfunction, decreased libido, and ejaculatory disorders compared to placebo. The absolute risk increase is small (roughly 2 to 4% above placebo), but it is not zero, and post-finasteride syndrome, while poorly understood and debated, is a reported phenomenon.

For men on TRT specifically, there is encouraging data. Borst et al. (2014) studied men receiving both TRT and finasteride and found that finasteride did not blunt the musculoskeletal benefits of testosterone replacement. Lean body mass, strength, and bone density improvements were preserved despite the reduction in DHT. This suggests that for men on therapeutic TRT doses, adding finasteride to protect hair does not undermine the primary benefits of testosterone therapy.

Dutasteride (0.5 mg daily)

Dutasteride inhibits both Type I and Type II 5-alpha reductase, reducing serum DHT by over 90%. A randomised phase III trial comparing dutasteride to finasteride showed that dutasteride produced superior hair count improvements at 24 weeks (Gubelin Harcha et al., 2014).

The trade-off: dutasteride has a much longer half-life (5 weeks versus 6 to 8 hours for finasteride), meaning side effects take longer to resolve if they occur. It is also not FDA-approved for hair loss in most countries (it is approved for benign prostatic hyperplasia), so use for AGA is off-label. The side effect profile is similar to finasteride but may be slightly more pronounced due to the deeper DHT suppression.

Topical minoxidil (5%)

Minoxidil is a vasodilator that extends the anagen (growth) phase and increases follicle size independently of the androgen pathway. A 48-week RCT found that 5% topical minoxidil produced significantly greater hair regrowth compared to 2% minoxidil, with a 45% greater total hair count increase (Olsen et al., 2002).

Minoxidil does not address the root cause (DHT), so it works best in combination with a 5-alpha reductase inhibitor. Used alone, it can slow visible thinning but may not prevent ongoing miniaturisation.

Low-dose topical finasteride

Topical finasteride (0.1% to 0.25%) applied to the scalp aims to reduce scalp DHT locally while minimising systemic absorption and side effects. Early evidence is promising, though head-to-head data against oral finasteride is limited. This is an option for men who want DHT suppression at the follicle level without the systemic effects of oral finasteride.

Ketoconazole shampoo (2%)

Ketoconazole has mild anti-androgenic properties at the follicle level and reduces scalp inflammation. Used 2 to 3 times per week as part of a broader protocol, it provides modest additive benefit. It is not a standalone treatment.

What to do before you start TRT (if you are worried about hair)

If hair preservation matters to you, take these steps before your first injection:

1. Document your baseline. Photograph your hairline and crown under consistent lighting. You cannot assess change without a reference point. Include front, top, and both temples.
2. Check your family history. Look at your maternal grandfather and uncles specifically. The primary genetic risk comes through the X chromosome.
3. Get baseline bloodwork including DHT. Most pre-TRT panels skip DHT. Request it so you can compare after starting treatment. Also check total testosterone, free testosterone, and SHBG. For the full list of what to test, see our TRT monitoring guide.
4. Choose your delivery method wisely. If you have a family history of AGA, injectable testosterone produces significantly less DHT than creams or gels. Discuss this with your prescriber.
5. Consider starting a preventive treatment. If your family history is strong and you are already seeing early thinning, starting finasteride (1 mg oral or topical) before TRT gives your follicles protection from the outset rather than playing catch-up.
6. Set a monitoring timeline. Take comparison photos every 3 months. Recheck DHT at your first follow-up blood draw (typically 6 to 8 weeks into TRT). If you are tracking your bloodwork with VitalMetrics, add DHT to your monitored markers so you can see the trend over time.

The worst approach is to avoid TRT you need because of hair fears without first assessing your actual risk. The second worst approach is to start TRT, panic at the first sign of shedding, and make impulsive changes to your protocol. Informed baseline assessment and a plan give you control.

Steroids beyond TRT: which compounds are worst for hair?

This section is relevant for bodybuilders using supraphysiological doses or multiple compounds. If you are on standard TRT (100 to 200 mg per week of testosterone), you can focus on the sections above. But if you are running cycles, compound choice has a dramatic impact on hair loss risk.

High risk: DHT derivatives

These compounds are either DHT itself or structurally derived from it. They do not need 5-alpha reductase to become androgenic, which means finasteride will not protect you from their effects (Bond et al., 2022).

• Masteron (drostanolone): A pure DHT derivative. Directly binds androgen receptors in hair follicles without conversion. One of the harshest compounds for hair.
• Winstrol (stanozolol): Another DHT derivative with strong androgenic activity at the follicle. Notorious for accelerating hair loss in susceptible users.
• Anavar (oxandrolone): Derived from DHT but with lower androgenic potency. Often marketed as "hair safe" but still carries risk in susceptible individuals because it directly activates the androgen receptor.
• Primobolan (methenolone): A DHT derivative considered milder than Masteron or Winstrol, but still a direct androgen receptor agonist. Not risk-free for hair.

Moderate risk: testosterone and boldenone

Testosterone at supraphysiological doses produces proportionally more DHT. At 500 mg per week, you are producing several times the DHT of a TRT dose. Finasteride can mitigate this, but the sheer substrate load may overwhelm partial inhibition.

Lower risk: nandrolone

Nandrolone (Deca-Durabolin) is an interesting case. It is reduced by 5-alpha reductase not to DHT but to dihydronandrolone (DHN), which has very low androgenic potency. DHN binds the androgen receptor at roughly 12% of DHT's affinity, making it far too weak to drive hair miniaturisation (Toth & Zakar, 1982). In practice, nandrolone is one of the least hair-aggressive anabolic steroids.

There is an important caveat, though: using finasteride with nandrolone actually increases its androgenic effects. By blocking 5-alpha reductase, you prevent the conversion of nandrolone to the weaker DHN, leaving more unmetabolised nandrolone to act on androgen receptors directly. Nandrolone itself has moderate receptor affinity. This is one scenario where finasteride makes hair loss worse, not better.

Special case: trenbolone

Trenbolone does not require 5-alpha reductase conversion. It is already a highly potent androgen receptor agonist with roughly three times the receptor affinity of testosterone (Yarrow et al., 2010). It directly activates androgen receptors in hair follicles, and finasteride offers no protection. If you are prone to AGA, trenbolone will accelerate hair loss substantially.

For a broader look at how different compounds affect your blood markers beyond hair, see our guides on liver enzymes on steroids and thyroid function on steroids.

Key takeaways

• TRT does not universally cause hair loss. It increases DHT, which accelerates androgenetic alopecia in genetically susceptible men. No genetic susceptibility, no hair loss from testosterone.
• Genetics is the dominant factor. The androgen receptor gene (AR) on the X chromosome determines how your follicles respond to DHT. Family history, particularly maternal, is your best predictor.
• Delivery method matters. Transdermal testosterone (creams, gels) raises DHT roughly 5.5x baseline versus 2.2x for injections. If hair is a concern, injectable testosterone is the lower-risk option.
• Serum DHT does not tell the whole story. Scalp tissue DHT and local receptor sensitivity matter more than a number on your blood panel. Track DHT for trends, but correlate with what you see in the mirror.
• Finasteride (1 mg daily) is the most effective pharmaceutical protection. It reduces scalp DHT by approximately 64% and does not blunt the musculoskeletal benefits of TRT.
• Do not use finasteride with nandrolone. Blocking 5-alpha reductase prevents nandrolone's conversion to the weaker DHN, paradoxically increasing its androgenic effect on hair follicles.
• DHT-derivative compounds (Masteron, Winstrol, Primobolan, Anavar) bypass 5-alpha reductase entirely. Finasteride cannot protect your hair from these compounds.
• Baseline documentation matters. Photograph your hairline, check family history, and test DHT before starting TRT. You cannot assess change without a reference point.

---

References

1. Kische, H., Gross, S., Wallaschofski, H., Volzke, H., Dorr, M., Nauck, M., & Haring, R. (2017). Sex Hormones and Hair Loss in Men From the General Population of Northeastern Germany. JAMA Dermatology, 153(9), 935-937. PubMed

2. Sawaya, M. E., & Shalita, A. R. (1998). Androgen receptor polymorphisms (CAG repeat lengths) in androgenetic alopecia, hirsutism, and acne. Journal of Cutaneous Medicine and Surgery, 3(1), 9-15. PubMed

3. Borst, S. E., Shuster, J. J., Zou, B., Ye, F., Jia, H., Wokhlu, A., & Yarrow, J. F. (2014). Cardiovascular risks and elevation of serum DHT vary by route of testosterone administration: A systematic review and meta-analysis. BMC Medicine, 12, 211. PubMed

4. Kaufman, K. D., Olsen, E. A., Whiting, D., Savin, R., DeVillez, R., Bergfeld, W., ... & Gormley, G. J. (1998). Finasteride in the treatment of men with androgenetic alopecia. Journal of the American Academy of Dermatology, 39(4), 578-589. PubMed

5. Gubelin Harcha, W., Barboza Martinez, J., Tsai, T. F., Katsuoka, K., Kawashima, M., Tsuboi, R., ... & Kaufman, K. D. (2014). A randomized, active- and placebo-controlled study of the efficacy and safety of different doses of dutasteride versus placebo and finasteride in the treatment of male subjects with androgenetic alopecia. Journal of the American Academy of Dermatology, 70(3), 489-498. PubMed

6. Borst, S. E., Yarrow, J. F., Conover, C. F., Nseyo, U., Meuleman, J. R., Lipinska, J. A., ... & Shuster, J. J. (2014). Musculoskeletal and prostate effects of combined testosterone and finasteride administration in older hypogonadal men: A randomized, controlled trial. American Journal of Physiology-Endocrinology and Metabolism, 306(4), E433-E442. PubMed

7. Tawanwongsri, W., Desai, D., Nohria, A., Shapiro, J., & Lo Sicco, K. (2025). Hair loss in anabolic androgenic steroid users: A narrative review. International Journal of Dermatology, 64(3), e70052. PubMed

8. Toth, M., & Zakar, T. (1982). Relative binding affinities of testosterone, 19-nortestosterone and their 5-alpha reduced derivatives to the androgen receptor and to other androgen-binding proteins. Endokrinologie, 80(2), 163-172. PubMed

9. Yarrow, J. F., McCoy, S. C., & Borst, S. E. (2010). Tissue selectivity and potential clinical applications of trenbolone (17beta-hydroxyestra-4,9,11-trien-3-one): A potent anabolic steroid with reduced androgenic and estrogenic activity. Steroids, 75(6), 377-389. PubMed

10. Zhang, Y., Xu, J., Jing, J., Wu, X., & Lv, Z. (2018). Serum levels of androgen-associated hormones are correlated with curative effect in androgenic alopecia in young men. Medical Science Monitor, 24, 7770-7777. PubMed

11. Olsen, E. A., Dunlap, F. E., Funicella, T., Koperski, J. A., Swinehart, J. M., Tschen, E. H., & Trancik, R. J. (2002). A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men. Journal of the American Academy of Dermatology, 47(3), 377-385. PubMed

12. Lee, S., Lee, Y. B., Choe, S. J., & Lee, W. S. (2019). Adverse sexual effects of treatment with finasteride or dutasteride for male androgenetic alopecia: A systematic review and meta-analysis. Acta Dermato-Venereologica, 99(1), 12-17. PubMed

13. Bond, P., Smit, D. L., & de Ronde, W. (2022). Anabolic-androgenic steroids: How do they work and what are the risks? Frontiers in Endocrinology, 13, 1059473. PubMed