How common are bald patches in alopecia areata?

Alopecia areata can create one or more clearly defined patches on the scalp, beard area, eyebrows or eyelashes. The skin within a patch may look smooth, without the scale or broken hairs seen in some infections. Short regrowing hairs, tapered hairs or changes at the edge can help a clinician assess activity, but appearance alone cannot confirm the cause.

Patches may enlarge, join together or be followed by regrowth. Hair loss elsewhere, nail changes, itch, tenderness or scaling should be mentioned because they can alter the assessment and may suggest another or additional scalp problem.

Arrange a dermatology assessment if a patch is new, expanding or repeatedly returning. The clinician may inspect the scalp closely, examine hairs and nails, and decide whether further testing is needed. Bring a list of medicines and note when the first patch appeared, whether shedding is continuing, and whether anyone in the family has similar episodes.

Protect exposed scalp from strong sunlight and cold, avoid tight hairstyles and handle the area gently. Do not apply steroid or hair-growth products to the scalp without advice, especially if there is scale, broken hair or possible infection.

Seek prompt assessment for rapidly expanding loss, widespread scalp involvement, eyebrow or eyelash loss, marked redness, pus, severe pain or swollen glands. Urgent care is appropriate for facial swelling, fever or eye symptoms. These signs need evaluation because they are not explained by every case of alopecia areata.

Does the pattern fit alopecia areata or another cause? Are the follicles still active in the patch? Do I need scalp or blood testing? Which treatment options suit the location and extent of loss?