Thyroid and Skin: How Thyroid Disorders Affect Your Skin

Hypothyroidism and Skin

An underactive thyroid slows metabolism throughout the body, directly affecting skin cell turnover, sweat and oil gland function, and hair growth. Skin changes include:

• Dry, rough skin (xerosis): The most common skin symptom, affecting up to 80% of hypothyroid patients. Reduced sweat and oil gland activity leads to extremely dry skin that may crack and scale.
• Cool, pale skin: Reduced blood flow and vasoconstriction give skin a pale, sometimes yellowish (carotenemia) appearance
• Myxedema: In severe hypothyroidism, a waxy, non-pitting swelling occurs in the face and limbs due to mucopolysaccharide deposits in the skin
• Hair loss: Diffuse thinning of scalp hair. Characteristically, the outer third of the eyebrow thins or disappears — a classic diagnostic sign. Hair becomes dry, coarse, and brittle.
• Brittle nails: Slow-growing, ridged, easily breakable nails
• Slow wound healing: Reduced cell turnover impairs repair mechanisms
• Easy bruising: From capillary fragility

Hyperthyroidism and Skin

An overactive thyroid accelerates metabolism, producing opposite effects:

• Warm, moist, smooth skin: Increased blood flow and sweating give skin a flushed, damp appearance
• Fine, thinning hair: Hair becomes silky-fine but diffusely thin. Hair growth cycle is shortened.
• Onycholysis: Separation of the nail from the nail bed, particularly in Graves' disease
• Pretibial myxedema: Thick, waxy, red-brown plaques on the shins — specific to Graves' disease. Affects about 1-4% of Graves' patients.
• Hyperpigmentation: Generalized darkening of the skin, particularly in skin folds
• Pruritus (itching): From increased blood flow and warm skin
• Urticaria (hives): Autoimmune thyroid disease is associated with chronic urticaria in some patients

Thyroid Autoimmunity and Skin

Autoimmune thyroid diseases (Hashimoto's thyroiditis, Graves' disease) are associated with other autoimmune skin conditions:

• Vitiligo: Autoimmune destruction of melanocytes, causing white patches
• Alopecia areata: Autoimmune hair loss causing circular bald patches
• Chronic urticaria: About 10-30% of patients with chronic hives have autoimmune thyroid antibodies
• Dermatitis herpetiformis: Associated with celiac disease, which commonly coexists with autoimmune thyroid disease

Diagnosis and Treatment

Key tests:

• TSH (thyroid-stimulating hormone) — the primary screening test
• Free T4 and free T3 — confirm the diagnosis
• Anti-TPO and anti-thyroglobulin antibodies — detect autoimmune thyroid disease

Skin recovery with treatment:

• Dry skin and hair loss from hypothyroidism typically improve within 2-6 months of starting levothyroxine
• Hair regrowth may take 6-12 months — be patient
• Hyperthyroid skin changes reverse with treatment (methimazole, radioiodine, or surgery)
• Pretibial myxedema may persist and require separate treatment (topical steroids under occlusion)

Frequently Asked Questions

My thyroid levels are normal but I'm still losing hair — could my thyroid still be the cause?

"Normal" TSH ranges vary. Some patients with TSH in the high-normal range (3-5 mIU/L) may benefit from treatment targeting a lower TSH. Additionally, check thyroid antibodies — autoimmune inflammation can affect hair even before TSH becomes abnormal. Discuss optimal (not just normal) thyroid levels with your doctor.

Will my eyebrows grow back?

In most cases, yes. Eyebrow thinning from hypothyroidism is reversible with adequate thyroid hormone replacement. Full regrowth may take 6-12 months. If the outer third remains thin despite normalized thyroid levels, microblading or eyebrow transplant can help cosmetically.

Should I get my thyroid checked if I'm losing hair?

Yes. Thyroid function testing (TSH, free T4) should be part of every hair loss evaluation, especially in women. Thyroid-related hair loss is one of the most treatable causes — missing it means missing an easy fix.