Usage
Coal tar combined with salicylic acid is primarily prescribed for inflammatory skin conditions such as psoriasis, seborrheic dermatitis (dandruff), and eczema. It is classified as a keratolytic and antipruritic agent. The combination works by breaking down the thickened, scaly skin and relieving itching.
Alternate Names
There are no widely recognized alternate generic names. Brand names vary depending on the formulation and country of origin but may include names like Sebitar or Denorex. Many formulations are marketed simply as “coal tar shampoo” or “coal tar ointment”.
How It Works
Pharmacodynamics: Coal tar slows rapid skin cell turnover, reducing scaling and inflammation. Salicylic acid softens and loosens the scales (keratolytic action), facilitating their removal. The combined effect reduces inflammation and relieves itching.
Pharmacokinetics: Coal tar, when applied topically, has minimal systemic absorption. Salicylic acid is absorbed percutaneously, with the extent of absorption depending on factors like the vehicle (ointment, cream, shampoo), concentration, and the condition of the skin. It is metabolized primarily in the liver and excreted by the kidneys.
Mode of Action: The exact mechanism of action of coal tar is not fully understood, but it’s believed to suppress DNA synthesis in epidermal cells, slowing their growth and reducing inflammation. Salicylic acid increases skin hydration and dissolves the intercellular “cement” holding skin cells together, leading to desquamation (shedding of the outer layer of skin).
Dosage
Standard Dosage
Adults:
- Shampoo: Massage into wet scalp, leave for several minutes, and rinse thoroughly. Frequency can vary from twice weekly to daily depending on the product and severity of the condition.
- Ointment/Cream/Lotion: Apply a thin layer to the affected areas once or twice daily.
Children:
- Dosage and frequency should be determined by a physician and will depend on age, weight, and the specific condition. Some products are not recommended for children under a certain age (e.g., 2 years).
Special Cases:
- Elderly Patients: Similar to adult dosing but start with lower concentrations and frequencies and increase as tolerated.
- Patients with Renal Impairment: Caution is advised due to potential salicylic acid accumulation. Dosages may need adjustment based on renal function.
- Patients with Hepatic Dysfunction: Exercise caution due to potential salicylic acid accumulation.
- Patients with Comorbid Conditions: No specific dosage adjustments are typically necessary, but individual patient assessment is recommended.
Clinical Use Cases
Coal tar and salicylic acid are generally not used in acute medical settings like intubation, surgical procedures, mechanical ventilation, ICU, or emergencies. Their primary use is for chronic skin conditions in outpatient settings.
Dosage Adjustments
Dose modifications should be based on patient tolerance, the severity of the skin condition, and the presence of renal or hepatic impairment.
Side Effects
Common Side Effects
- Skin irritation (burning, stinging, redness)
- Photosensitivity (increased sensitivity to sunlight)
- Staining of skin, hair, and clothing
- Folliculitis (inflammation of hair follicles)
Rare but Serious Side Effects
- Allergic reactions (rash, itching, swelling, difficulty breathing)
Long-Term Effects
- Potential for skin atrophy (thinning) with prolonged, high-potency topical corticosteroid use (if combined in the formulation). Coal tar itself does not typically cause skin atrophy.
Contraindications
- Hypersensitivity to coal tar or salicylic acid.
- Application to open wounds or broken skin.
- Severe inflammation or acutely inflamed psoriasis.
Drug Interactions
- No significant drug-drug interactions are typically reported with topical coal tar and salicylic acid.
- Concomitant use of other topical medications on the same area should be done with caution.
- Phototherapy (UV light treatment) should be avoided immediately after coal tar application due to increased photosensitivity.
Pregnancy and Breastfeeding
Limited data are available regarding the safety of coal tar and salicylic acid during pregnancy and breastfeeding. Consult a physician before use.
Drug Profile Summary
- Mechanism of Action: Reduces skin cell turnover (coal tar), keratolytic action (salicylic acid).
- Side Effects: Skin irritation, photosensitivity, staining, folliculitis.
- Contraindications: Hypersensitivity, open wounds.
- Drug Interactions: Limited drug interactions. Avoid concomitant phototherapy.
- Pregnancy & Breastfeeding: Consult a physician.
- Dosage: Varies depending on product and condition; see detailed dosage section.
- Monitoring Parameters: Monitor for skin irritation, allergic reactions, and treatment efficacy.
Popular Combinations
Coal tar is often combined with salicylic acid, sulfur, or topical corticosteroids in various formulations.
Precautions
- General Precautions: Avoid contact with eyes and mucous membranes. Test on a small area of skin before widespread use.
- Specific Populations: Consult a physician before use during pregnancy or breastfeeding, or in children.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Coal Tar + Salicylic Acid?
A: Dosage varies depending on the product, the condition being treated, and the patient’s age. Refer to the detailed dosage section above.
Q2: How often should I use a coal tar shampoo?
A: Typically twice a week to daily as directed by a physician or product labeling.
Q3: Can coal tar and salicylic acid be used on the face?
A: Use with caution on the face due to the potential for irritation. Avoid contact with eyes and mucous membranes.
Q4: Can coal tar stain clothes and hair?
A: Yes, coal tar can stain. Use caution and protect clothing and bedding.
Q5: Is it safe to use coal tar and salicylic acid during pregnancy?
A: Consult a physician before use during pregnancy or while breastfeeding.
Q6: What should I do if I experience skin irritation?
A: Discontinue use and consult a physician.
Q7: Can coal tar and salicylic acid be used with other topical medications?
A: Use with caution. Consult with a physician before combining with other topical treatments, particularly corticosteroids.
Q8: Does coal tar increase the risk of skin cancer?
A: While some studies have shown a potential link between high concentrations of coal tar and skin cancer in animal models, topical coal tar used as directed is generally considered safe.
Q9: How long does it take to see results with coal tar and salicylic acid treatment?
A: Improvement may be seen within a few weeks, but it can take several months for optimal results.
