The Bottom Line

Male pattern baldness (androgenetic alopecia) follows predictable patterns classified by the Norwood Scale, from minor temple recession (stage II) to extensive loss leaving only a horseshoe ring of hair (stage VII). It affects approximately 50% of men by age 50 and 80% by age 70. Treatment effectiveness depends heavily on stage — earlier intervention yields significantly better outcomes.

The Norwood Scale Explained

The Hamilton-Norwood Scale, developed in the 1950s and refined in 1975, classifies male pattern baldness into seven stages:

  • Stage I: No significant hair loss or recession — baseline
  • Stage II: Slight recession at the temples — often called a "mature hairline." This is normal adult hair positioning and may not require treatment.
  • Stage III: First stage considered clinically bald. Deepening temple recession forming an M, U, or V shape. Stage III vertex shows thinning at the crown.
  • Stage IV: More severe hairline recession and significant thinning at the crown. A band of moderate-density hair still separates the two areas.
  • Stage V: The band between hairline recession and crown thinning narrows considerably. Overall hair density is low.
  • Stage VI: The bridge of hair between the front and crown is lost. The balding areas merge.
  • Stage VII: The most advanced stage. Only a narrow band of hair remains around the sides and back of the head (the "horseshoe" pattern).

What Causes Male Pattern Baldness

It's driven by genetics and the hormone DHT (dihydrotestosterone):

  • Testosterone is converted to DHT by the enzyme 5-alpha reductase
  • In genetically susceptible hair follicles, DHT causes progressive miniaturization — follicles produce thinner, shorter, less pigmented hairs until they stop producing visible hair entirely
  • The pattern is genetic, inherited from either parent (not just the mother's side, as the common myth suggests)
  • Hair on the sides and back of the head lacks DHT-sensitive receptors, which is why it's "permanent" and used as donor hair for transplants

Treatment by Stage

Stages II-III (early):

  • Finasteride 1mg daily: Blocks 70% of DHT. Stops progression in 83% of men and regrows hair in 66% over 2 years. This is the most important medication at early stages.
  • Minoxidil 5% (Rogaine): Topical, applied twice daily. Works by extending the anagen (growth) phase. Effective on the crown; less so on the hairline. Can be used alongside finasteride.
  • Low-level laser therapy: FDA-cleared devices may modestly improve density as an adjunct.

Stages III-V (moderate):

  • All of the above, plus consideration of hair transplant surgery
  • FUE or FUT transplant: 1,500-3,000 grafts to restore the hairline and fill thinning areas. Best combined with ongoing finasteride to prevent further loss of non-transplanted hair.
  • PRP (platelet-rich plasma): Adjunctive treatment injected into the scalp to boost growth factors

Stages VI-VII (advanced):

  • Transplant options become more limited due to reduced donor supply
  • Medications can still prevent further loss and modestly improve density
  • Realistic expectations are essential — complete restoration is not possible at advanced stages
  • Scalp micropigmentation (cosmetic tattooing that creates the appearance of a close-shaved head) is an effective non-surgical option

Frequently Asked Questions

At what age should I start treatment?

As soon as you notice thinning or your dermatologist identifies early signs. Starting finasteride at Norwood II-III is far more effective than waiting until stage V. The goal is to preserve existing hair — which is easier than regrowing lost hair.

What about finasteride side effects?

Sexual side effects (decreased libido, erectile dysfunction) affect about 2-4% of men in clinical trials and are reversible upon stopping. Post-finasteride syndrome (persistent side effects after discontinuation) has been reported but is controversial and not established as a distinct medical condition in large studies. Discuss concerns with your dermatologist.

Can I determine my Norwood stage myself?

You can get a rough idea by comparing your hair pattern to Norwood Scale images. However, a dermatologist can perform a more accurate assessment using dermoscopy (magnified scalp examination) that detects miniaturization invisible to the naked eye — often identifying early loss before it's visibly obvious.

  1. Norwood OT. "Male pattern baldness: classification and incidence." Southern Medical Journal. 1975;68(11):1359-1365.
  2. Adil A, Godwin M. "The effectiveness of treatments for androgenetic alopecia." JAAD. 2017;77(1):136-141.
  3. Kaufman KD, et al. "Finasteride in the treatment of men with androgenetic alopecia." JAAD. 1998;39(4):578-589.