Alopecia areata is not caused by DHT (dihydrotestosterone), and DHT-blocking treatments like finasteride will not treat this condition. This is one of the most common sources of confusion in hair loss, because both alopecia areata and androgenetic alopecia cause visible thinning or baldness, yet their underlying mechanisms are entirely different. Understanding the distinction is critical for choosing the right treatment.
This article is for informational purposes only and does not constitute medical advice.
DHT and Androgenetic Alopecia: A Quick Overview
DHT is the primary hormonal driver behind androgenetic alopecia (male and female pattern hair loss). The enzyme 5-alpha reductase converts testosterone into DHT, which then binds to androgen receptors on genetically susceptible hair follicles. Over time, DHT causes those follicles to miniaturize, producing thinner and shorter hairs until they stop growing altogether.
Finasteride, a 1mg daily oral medication, blocks 5-alpha reductase and reduces scalp DHT levels. It halts further hair loss in 80 to 90% of men with androgenetic alopecia and produces regrowth in approximately 65% of users, with side effects occurring in only 2 to 4% of patients.
This mechanism is well understood and well treated. But it has nothing to do with alopecia areata.
Why Alopecia Areata Is Not a DHT Problem
Alopecia areata is an autoimmune disorder. Instead of hormones attacking follicles, the immune system itself targets them. T-lymphocytes (a type of white blood cell) swarm around the hair bulb, the deepest part of the follicle, and trigger it to prematurely enter the catagen (regression) phase and then the telogen (resting) phase. The follicle shrinks, hair falls out, and regrowth stalls.
Key differences between the two conditions:
| Feature | Androgenetic Alopecia | Alopecia Areata |
|---|---|---|
| Cause | DHT-driven miniaturization | Autoimmune attack on follicles |
| Pattern | Gradual thinning at temples, crown | Sudden round or oval patches |
| Onset | Progressive over years | Rapid, often within weeks |
| Follicle damage | Miniaturization (shrinking) | Inflammatory arrest (sleeping) |
| DHT blocker response | Effective (80-90% halt loss) | Not effective |
| First-line treatment | Finasteride or minoxidil | Corticosteroid injections or JAK inhibitors |
| Reversibility | Partial with ongoing treatment | Spontaneous remission possible in 50% |
The follicles in alopecia areata are not miniaturized by hormones. They are structurally intact but forced into dormancy by immune activity. This is why the condition can reverse spontaneously, something that rarely happens with untreated androgenetic alopecia.
Can You Have Both Conditions Simultaneously?
Yes. Having alopecia areata does not protect you from androgenetic alopecia, and vice versa. Some patients experience overlapping conditions, which complicates diagnosis and treatment.
Signs you may have both include gradual thinning in typical pattern loss areas (temples, crown) alongside sudden smooth patches elsewhere on the scalp. A dermatologist can differentiate between the two using dermoscopy, which reveals different follicular patterns for each condition, or a scalp biopsy if necessary.
If both conditions are present, you may need a combination approach: DHT-blocking medication like finasteride for the androgenetic component, and immune-modulating treatment for the alopecia areata component. Misdiagnosis of hair loss type leads to the wrong treatment in roughly 28% of cases, so accurate identification of each condition is essential. Learn more about the root alopecia areata causes to understand these differences.
Hormonal Factors That Do Affect Alopecia Areata
While DHT is not the trigger, hormones can still influence alopecia areata in indirect ways.
Thyroid Hormones
Thyroid disorders, both hypothyroidism and hyperthyroidism, are significantly more common in people with alopecia areata than in the general population. The connection is autoimmune: if your immune system attacks hair follicles, it is more likely to also target the thyroid gland. Blood tests for TSH, T3, and T4 should be part of any alopecia areata workup.
Cortisol and Stress Hormones
Psychological and physical stress can trigger or worsen alopecia areata flare-ups through the hypothalamic-pituitary-adrenal (HPA) axis. Elevated cortisol and other stress hormones can dysregulate immune function, potentially tipping a predisposed individual into an active autoimmune episode. This is why many patients report that their first patch appeared during a period of significant stress.
Sex Hormones During Life Transitions
Pregnancy, postpartum periods, menopause, and puberty involve significant hormonal shifts that can coincide with alopecia areata onset or flare-ups. These transitions do not cause the condition through DHT pathways, but the immune system remodeling that occurs during hormonal transitions may create a window of vulnerability.
Why Finasteride Does Not Work for Alopecia Areata
Finasteride specifically reduces DHT by approximately 70% in the scalp. Since alopecia areata is driven by immune cell infiltration around the follicle bulb, not by DHT-mediated miniaturization, reducing DHT levels provides no benefit. Multiple studies have confirmed that finasteride is ineffective for alopecia areata.
Taking finasteride for alopecia areata is not harmful, but it wastes time and money while the actual autoimmune process continues unchecked. If you have been prescribed finasteride without a confirmed diagnosis, ask your dermatologist to re-evaluate whether your hair loss pattern is truly androgenetic or autoimmune in origin.
Treatments That Actually Work for Alopecia Areata
Effective treatments target the immune system rather than hormones:
- Intralesional corticosteroid injections: First-line for limited patches, with 60 to 70% response rates and regrowth visible in 4 to 8 weeks
- JAK inhibitors (baricitinib, ritlecitinib): FDA-approved for severe cases, with 35 to 40% achieving 80% or greater coverage after 36 weeks
- Topical immunotherapy (DPCP, SADBE): Used for extensive patches that do not respond to injections
- PRP therapy: Costs $500 to $2,000 per session with 30 to 40% density increase in studies, sometimes used as an adjunct treatment
- Minoxidil: Produces moderate regrowth in 40 to 60% of users as a supporting treatment, though it does not address the autoimmune cause
Determining Your Type of Hair Loss
Correctly identifying whether your hair loss is hormonal, autoimmune, or both is the single most important step in treatment. A sudden, smooth, round patch is the hallmark of alopecia areata. Gradual diffuse thinning at the hairline or crown suggests androgenetic alopecia. If you are unsure which type you have, getting an assessment is essential before starting any medication. Check your hair transplant candidacy to understand what options may be available for your specific situation.
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