Psoriasin / T-Gel

Drug Overview

Coal Tar is a foundational medication in the field of Dermatology. Although it is one of the oldest treatments used for skin conditions, it remains a highly effective, widely accessible therapeutic option. It belongs to the Keratoplastic and Keratolytic drug classes, meaning it helps normalize skin cell growth and promotes the shedding of dead skin cells.

Here are the essential details about this medication:

• Generic Name: Coal Tar
• US Brand Names: Psoriasin / T-Gel, Neutrogena T/Gel, Denorex, MG217
• Drug Category: Dermatology
• Drug Class: Keratoplastic / Keratolytic Agent
• Route of Administration: Topical (applied directly to the skin or scalp as a shampoo, gel, ointment, or cream)
• FDA Approval Status: FDA-approved (available as an Over-The-Counter monograph drug and in higher prescription strengths)

What Is It and How Does It Work? (Mechanism of Action)

Coal tar is a complex, thick, dark liquid byproduct of the distillation of bituminous coal. It contains thousands of distinct chemical compounds, primarily polycyclic aromatic hydrocarbons.

For decades, exactly how coal tar worked was a mystery, but modern science has revealed its molecular mechanism of action. When applied to the skin, the compounds in coal tar penetrate the cells and bind to a specific protein inside the cell called the Aryl hydrocarbon receptor (AhR).

1. AhR Activation: Binding to the AhR triggers a signaling pathway that travels directly into the cell’s nucleus.
2. Gene Regulation: Once in the nucleus, it alters how specific genes are expressed. It essentially “turns down” the genes responsible for severe inflammation and rapid cell growth.
3. Restoring Normal Skin Shedding (Keratopoiesis): In conditions like psoriasis and dandruff, skin cells multiply too rapidly and pile up on the surface. By suppressing DNA synthesis in these hyperactive skin cells (keratinocytes), coal tar slows down their reproduction rate.
4. Antimicrobial and Anti-itch Effects: Coal tar also possesses mild antibacterial and antifungal properties (disrupting cell membranes of skin flora like Malassezia yeast, which contributes to dandruff) and numbs the nerve endings in the skin, providing a strong anti-pruritic (anti-itch) effect.

FDA-Approved Clinical Indications

Primary Indication

• Psoriasis, Dandruff, and Seborrheic Dermatitis: Coal tar is specifically approved for the relief of scaling, itching, flaking, and redness associated with mild to moderate forms of these chronic skin and scalp conditions.

Other Approved Uses

• Atopic Dermatitis (Eczema): Used off-label or as a general medical treatment to manage thick, scaly, and itchy eczema plaques.
• Goeckerman Therapy: A specialized clinical treatment combining crude coal tar application with ultraviolet B (UVB) phototherapy for severe, widespread psoriasis.

Dosage and Administration Protocols

Coal tar formulations vary significantly in concentration (ranging from 0.5% to 5%). The exact dosage depends on the specific product (shampoo vs. topical ointment) and the severity of the condition.

Dose Adjustments and Special Populations:

• Renal and Hepatic Insufficiency: Because systemic absorption (how much enters the bloodstream) is extremely low when used as directed, no dose adjustments are required for patients with kidney or liver impairment.
• Pediatric Patients: Use in children under 2 years of age should only be done under the strict supervision of a physician.

Clinical Efficacy and Research Results

Despite the advent of modern treatments, coal tar remains a highly effective option. Recent dermatological reviews and clinical analyses (2020–2026) reaffirm its clinical value:

• Symptom Reduction: In mild to moderate plaque psoriasis, modern analyses show that standard coal tar therapy achieves a PASI 50 (a 50% reduction in the Psoriasis Area and Severity Index score) in approximately 40% to 50% of patients after 4 to 8 weeks of consistent use.
• Scalp Conditions: For dandruff and seborrheic dermatitis, clinical evaluations show that 1% coal tar shampoo reduces visual flaking and scalp itching by over 60% within the first two weeks of bi-weekly use.
• Combination Efficacy: When used in Goeckerman therapy (coal tar + UVB light), complete clearance or near-complete clearance of severe psoriasis plaques is achieved in 80% to 100% of patients, with remissions frequently lasting longer than those seen with some newer systemic medications.

Safety Profile and Side Effects

Common Side Effects (Occurring in >10% of patients)

• Strong, distinctive, and unpleasant odor
• Staining of the skin, hair (especially light-colored hair), and clothing
• Skin irritation, redness, or a mild burning sensation upon application
• Increased sensitivity to sunlight (Photosensitivity)

Serious Adverse Events

• Folliculitis: Inflammation or infection of the hair follicles caused by the tar clogging the pores.
• Allergic Contact Dermatitis: A severe local allergic reaction characterized by extreme redness, swelling, and worsening itch.
• Note on Carcinogenicity: While raw industrial coal tar contains known carcinogens, large-scale, long-term epidemiological studies have shown that therapeutic use of cosmetic/pharmaceutical grade coal tar on the skin does not significantly increase the risk of skin cancer or systemic malignancies.

Management Strategies

• To manage photosensitivity, patients must apply sunscreen and wear protective clothing over treated areas when going outdoors.
• If folliculitis occurs, the treatment should be temporarily stopped, and the area should be washed with a gentle, non-comedogenic cleanser.
• To minimize staining, allow topical gels and ointments to dry completely before dressing, or wear designated older clothing during treatment periods.

Research Areas

While coal tar is not a regenerative medicine or cellular therapy, contemporary dermatological research (2024-2026) is heavily focused on modernizing this traditional drug. Because coal tar’s odor, messiness, and staining often lead to poor patient compliance, pharmaceutical researchers are developing advanced delivery systems. Clinical trials are currently testing nano-emulsions and liposomal encapsulation of coal tar. These microscopic delivery systems aim to transport the active hydrocarbon compounds directly into the deeper layers of the epidermis without leaving a messy, smelly residue on the skin surface, significantly improving the patient experience while maintaining high clinical efficacy.

Patient Management and Practical Recommendations

Pre-Treatment Tests

• Patch Test: Before applying coal tar to large areas of the body, apply a small amount to a discrete patch of skin (like the inside of the forearm) and wait 24 hours to ensure no severe allergic reaction occurs.
• Visual Inspection: A healthcare provider should confirm the diagnosis, as applying coal tar to broken, blistered, or acutely inflamed/infected skin can worsen the condition.

Precautions During Treatment

• Sun Vigilance: Coal tar makes your skin highly sensitive to ultraviolet (UV) light. You can burn much faster than normal. Avoid direct sunlight and tanning beds for at least 24 hours after application unless specifically directed by a doctor as part of phototherapy.
• Application Areas: Avoid applying coal tar to the genitals, groin, or face unless explicitly instructed by a dermatologist. Keep the medication strictly out of the eyes.

Do’s and Don’ts

• DO wash your hands thoroughly with soap and water immediately after applying coal tar creams or ointments.
• DO use a gentle, fragrance-free moisturizer alongside your coal tar treatment to help manage dry, irritated skin.
• DO follow the exact leave-on times for shampoos; rinsing too early reduces effectiveness.
• DON’T apply coal tar to open wounds, bleeding skin, or actively oozing sores.
• DON’T use coal tar for prolonged periods (months at a time) over very large areas of the body without regular check-ins with your dermatologist.

Legal Disclaimer

The information provided in this guide is for educational and informational purposes only and does not constitute medical advice. It is not intended to be a substitute for professional medical diagnosis, treatment, or clinical guidance. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment plan. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.