The Hair Scripts Response Test
Why 1 in 3 people don't respond to minoxidil — and how to know before you start
The SULT1A1 enzyme converts topical minoxidil into its active form. Without it, the medication cannot work — no matter the dose or consistency. Hair Scripts tests your enzyme activity before prescribing.
The science behind non-response
How topical minoxidil is supposed to work
Topical minoxidil must be converted by the scalp enzyme SULT1A1 (sulfotransferase 1A1) into minoxidil sulfate — the biologically active form that dilates blood vessels, prolongs the hair growth phase (anagen), and stimulates follicles.
Why it fails for 30–50% of users
Genetic variation means SULT1A1 activity differs dramatically between individuals. Those with low enzyme activity (Grade 1 on the patch test) cannot convert minoxidil efficiently — producing minimal minoxidil sulfate regardless of how much is applied topically.1
| Approach | SULT1A1 required? | Works for low converters? | Hair Scripts offers |
|---|---|---|---|
| Standard topical minoxidil (Rogaine) | Yes — required | No | — |
| Custom compounded topical (8% / 10%) | Yes — required | No (same mechanism) | ✓ With SULT1A1 test to confirm grade first |
| Oral minoxidil capsule (1 mg / 2.5 mg) | No — systemic absorption | Yes | ✓ For Grade 1 and Grade 2 patients |
| Topical + oral combination | Partial | Yes | ✓ Most effective for Grade 2–4 |
The SULT1A1 grade scale
The DOPA dye patch test produces a color reaction on the inner forearm. Your provider reads the grade and builds your treatment plan accordingly.
High SULT1A1 activity — topical minoxidil will work well. Recommend 10% topical serum.
Good converter — topical minoxidil effective. Start with 8% and reassess.
Low-moderate converter — topical may work partially. Consider combination with oral.
Low SULT1A1 — topical minoxidil unlikely to work. Switch to oral minoxidil capsule.
How the Hair Scripts Response Test works
Request your kit
Check the test kit box during your Hair Scripts intake quiz. The kit ships free with your consultation, arriving in 3–5 business days.
Apply the patch at home
Apply a small amount of DOPA dye to your inner forearm. Takes less than 1 minute. No medical training required.
Wait 30 minutes
The dye reacts with your SULT1A1 enzyme activity. The resulting color indicates your grade (1–4).
Photograph and upload
Take a clear photo and upload it to your patient portal. Your provider interprets the result within 24 hours.
Receive your prescription
Your provider prescribes the formulation calibrated to your grade — topical, oral, or both.
Frequently asked questions
What is the SULT1A1 enzyme?
SULT1A1 (sulfotransferase 1A1) is an enzyme found in the scalp that converts topical minoxidil into minoxidil sulfate — its active form. Without sufficient SULT1A1 activity, topical minoxidil cannot stimulate hair regrowth.
Why doesn't minoxidil work for everyone?
Studies show 30–50% of people have low SULT1A1 activity. These 'low converters' cannot efficiently activate topical minoxidil. For them, oral minoxidil — which is metabolized systemically — is typically far more effective.
Is the SULT1A1 test available anywhere else?
The DOPA dye patch test has been used in dermatology research for decades but is rarely offered by consumer telehealth platforms. Hair Scripts is among the only telehealth providers to include it as part of standard intake.
What if I'm a Grade 1 (non-responder)?
Your provider will recommend oral minoxidil (1 mg for AFAB, 2.5 mg for AMAB) rather than topical. Oral minoxidil bypasses scalp SULT1A1 entirely and works through systemic circulation.
Does insurance cover the test?
The test kit is included free with your Hair Scripts consultation. Hair Scripts does not bill insurance — all pricing is direct-pay and transparent.
References: Buhl AE et al. (1990) PMID 2230218; Goren A et al. (2014) PMID 24283387; Messenger AG, Rundegren J (2004) PMID 14996087.
Know your grade before you start
Complete the intake quiz and request your Hair Scripts Response Test kit. Ships free to Arizona.
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