Two genetically identical men started with the same baseline beard density. One applied ¾ cap of 5% minoxidil foam every morning for 16 months. The other did nothing. At month 16, their beards were dramatically, visibly different — in both hair count and density in the beard and mustache areas. Same genetics. The only variable was the decision to act.
The Study: What It Was and Why It Matters
The Shokravi and Zargham 2024 case report — published in SAGE Open Medical Case Reports in February 2024, from the University of British Columbia — is unique in the minoxidil beard literature. Most beard studies use placebo-controlled trials with groups of unrelated men. This one used something better: genetically identical twins.
Identical (monozygotic) twins share essentially 100% of their DNA. Same androgen receptor genes. Same 5-alpha reductase activity. Same androgen sensitivity. Same follicle density potential. Same hormonal environment. If you want to isolate the effect of a treatment while controlling for every genetic variable, twins are the closest thing to a perfect control that human biology allows.
The Setup: Two Identical Men, One Decision
Before the study began, both twins were assessed for baseline beard density. The researchers confirmed they had similar pre-treatment coverage — a necessary validation to ensure neither twin started with a meaningful advantage. Hair counts and density photographs established the baseline.
Applied minoxidil daily
- Started with 5% liquid minoxidil
- Switched to 5% foam at week 3 (skin dryness)
- Applied ¾ cap (~1.5g) once daily
- Continued for the full 16 months
- Used moisturizer to manage skin dryness
- Experienced shedding at ~month 3
- Continued through the shed
Applied nothing
- No minoxidil
- No other hair growth treatments
- Normal grooming only
- Same genetic profile
- Same hormonal environment
- Same diet, same lifestyle
- Served as the genetic control
Month by Month: What Actually Happened
Month 1. Twin A noticed the first subtle signs — new, finer, lighter hairs beginning to emerge in areas that were previously sparse. Not dramatic. Barely visible. The kind of thing you only catch with close inspection under good lighting. Twin B: unchanged.
Month 2. A modest increase in density visible to Twin A on close inspection. Still not the kind of change strangers would comment on. The foam was working on his skin better than the liquid had in week 1–3 — the switch had been the right call. Twin B: unchanged.
Month 3. The shed. More hairs than usual when Twin A touched his beard. Hairs on the sink. Hairs on the pillow. The kind of thing that makes most men stop and think they've made a mistake. Twin A continued. This was documented in the study as telogen effluvium — a normal phase transition, not a failure signal. Twin B: unchanged.
Months 4–8. Recovery and growth. The shedding resolved. Coverage began improving in ways that were visible from normal social distance. The beard and mustache areas showing meaningful density improvement. Twin B: still essentially the same as month 1.
Months 9–16. Continued progression. Hairs thickening, darkening. Terminal conversion underway. By month 16, the difference between the two twins was dramatic — not subtle, not "if you look closely" — clearly different to anyone who saw them together. Same DNA. Same parents. Same everything. One decision, made at month 1, visible from across the room at month 16.
What Side Effects Did the Treated Twin Experience?
The study documented the side effects honestly — which is part of what makes it a useful clinical document rather than promotional material.
- →Significant dry flaky skin with liquid formula (weeks 1–3) → resolved by switching to foam
- →Increased body hair — documented. A consequence of mild systemic absorption of topical minoxidil through the highly vascular facial skin.
- →Telogen effluvium at month 3 — documented. Temporary. Resolved.
- →No serious adverse effects — no cardiac symptoms, no significant edema, no discontinuation required.
What the Study Said About Permanence
The researchers specifically addressed the permanence question — one of the most common concerns men have before starting. Their conclusion was carefully hedged but meaningful:
The study noted that "the potential for permanence of minoxidil-induced facial hair is intriguing and may be due to the androgen paradox." It acknowledged "informal reports suggest terminal facial hairs gained while on minoxidil persist after cessation" — while correctly noting no formal RCT has studied this specifically. The researchers' own framing pointed toward mechanistic plausibility for permanence without overclaiming the evidence.
What This Study Proves — And What It Doesn't
The twin study is the most compelling real-world evidence for minoxidil beard growth. But it's also a single-case study — two subjects, no randomization, no blinding. It can't be the only evidence you rely on. What it does prove, definitively:
- ✓Genetic differences are not responsible for the dramatic before-and-after results you see — the genetics were identical here.
- ✓5% minoxidil foam, once daily, applied consistently for 16 months, produces real, measurable, visible beard growth.
- ✓The side effects (skin dryness, body hair increase, month 3 shed) are documented and manageable.
- ✓DNA is not destiny. The decision to act on it is a variable the study isolated directly.
Your Genetics Set the Ceiling. You Decide How Close You Get.
The twin study proved it. Start with the same protocol that produced those results — 5% foam, once daily. Happy Head's prescription formula gives you even better absorption from day one.
FAQ
Yes — it was published in SAGE Open Medical Case Reports in February 2024, a peer-reviewed journal. It is a case report (two subjects), not a randomized controlled trial, which means it sits lower on the evidence hierarchy than the Ingprasert 2016 RCT or the Almutairi 2025 systematic review. Its value is in providing a uniquely controlled real-world example — identical genetics — that RCTs with random subjects can't replicate.
Skin dryness and flaking caused by the propylene glycol in the liquid formula. This happened within the first 3 weeks. Foam formulations don't contain propylene glycol in most brands (Rogaine, Kirkland foam), which is why they're far gentler on facial skin. The switch didn't reduce efficacy — the 16-month results were achieved with foam for essentially the entire documented period.
Possibly — the Ingprasert RCT used twice daily and showed significant results at 16 weeks. But the twin study showed dramatic results at 16 months with once daily. The difference between once and twice daily may affect the timeline (faster early results with twice daily) but likely not the maximum achievable terminal outcome given enough time. The twin study demonstrates that once daily is sufficient for a full transformation.