Is Coal Tar Shampoo Safe for Psoriasis?
Yes, coal tar shampoo is approved and commonly used to treat scalp psoriasis. The FDA classifies coal tar as safe and effective for this condition at concentrations up to 5% in over-the-counter products.[1] It slows skin cell growth, reduces inflammation, scaling, and itching by targeting the hyperproliferation of keratinocytes in psoriatic plaques.
How Does It Work and What Results to Expect?
Coal tar penetrates the skin to suppress DNA synthesis in rapidly dividing cells, a hallmark of psoriasis. Studies show it clears mild to moderate scalp psoriasis in 50-70% of users after 4-8 weeks of daily or twice-weekly use, often combined with salicylic acid for better scale removal.[2][3] Improvement typically starts within 1-2 weeks, but full clearing may take a month.
Common Brands and How to Use It
Popular options include Neutrogena T/Gel (2% coal tar), MG217 Psoriasis Shampoo (3%), and DHS Tar Gel (5% extract). Wet hair, apply a small amount, lather for 5-10 minutes, then rinse. Use 2-3 times weekly; alternate with regular shampoo to avoid dryness. For best results, apply directly to plaques and leave on longer if tolerated.[1][4]
Potential Side Effects and Precautions
It can cause scalp irritation, dryness, or redness in 10-20% of users, especially at higher strengths—dilute or reduce frequency if this occurs. Strong odor and temporary hair staining are common. Avoid if allergic to coal tar or during pregnancy (Category C due to limited data).[2] Not for open wounds or severe cases; consult a doctor first. UV exposure after use may increase burns, so use sunscreen on scalp.
Who Should Avoid It or Use Alternatives?
Skip if you have fair skin prone to irritation or prefer odorless options. Alternatives include salicylic acid shampoos (e.g., DHS Sal), corticosteroid lotions like fluocinonide, or calcipotriene foam. For moderate-severe psoriasis, topical combos or biologics like etanercept outperform coal tar alone.[3][5] Phototherapy pairs well with it for stubborn cases.
Does It Interact with Other Psoriasis Treatments?
Safe with most topicals, but avoid mixing with dandruff shampoos containing selenium sulfide on the same day to prevent excessive drying. No major issues with oral meds like methotrexate, but inform your dermatologist.[2]
[1]: FDA Topical Analgesic/Coal Tar Labeling
[2]: American Academy of Dermatology: Coal Tar for Psoriasis
[3]: Journal of the American Academy of Dermatology: Coal Tar Efficacy Review (2018)
[4]: National Psoriasis Foundation: Shampoo Guide
[5]: Cochrane Review: Topical Treatments for Scalp Psoriasis (2020)