Coal tar is indicated for the symptomatic management of pruritus and irritation caused by dandruff, seborrheic dermatitis, atopic dermatitis, eczema, and psoriasis. Treatment with coal tar and UV light or sunlight can be beneficial because of its photosensitizing action. Official USP coal tar preparations include crude coal tar, coal tar topical solution, and coal tar ointment. Crude coal tar is produced as a byproduct secondary to the destructive distillation of coal, and it can be further refined into coal tar topical solution or ointment. Commercially available preparations that are not officially recognized by USP and do not have specifications for composition include coal tar extract and distillate. Application of crude coal tar preparations may be aesthetically displeasing to the patient; however, further refined products are believed by many clinicians to be therapeutically inferior. It has been suggested that the variability in refining processes may be responsible for differences in therapeutic response to coal tar preparations.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
NOTE: Coal tar preparations should not be used in children under 2 years of age, except under the direction of a physician.
Route-Specific Administration
Topical Administration
-Coal tar is applied topically and is for external use only. Do not apply in or near the anogenital area unless directed by a physician.
Cream/Ointment/Lotion Formulations
-Cream or ointment: Apply enough to cover affected area and rub in gently.
-Lotion: Shake well. Wash affected area to remove loose scales prior to application. Apply to affected areas using a small wad of cotton. Allow to air dry before contact with clothing.
Other Topical Formulations
-Foam: Apply enough to cover affected area and rub in gently.
-Shampoo: Wet hair with lukewarm water; massage in shampoo then rinse; repeat application and leave in for 5 minutes; rinse thoroughly.
-Cleansing bar or gel: Apply enough gel to cover affected area and rub in gently; leave on for 5 minutes, then remove excess.
-Solution: May be used full strength or diluted in 3 parts water and applied to a cotton or gauze pad and then massaged gently into the affected area. Alternatively, a bath may be prepared by adding 4 to 6 tablespoonfuls to a tub of lukewarm water.
Prolonged periods of coal tar application can result in dermatitis that can be severe. A contact dermatitis can develop, with the latter increasing in severity with increasing concentrations of the drug.
Application of coal tar over an extended period can result in an asymptomatic, chronic folliculitis. This reaction generally subsides following discontinuance of treatment or reduction in the frequency of application. The occurrence of folliculitis can be reduced by: avoiding application to areas with hair, if possible; shortening treatment duration; and avoiding occlusion of treated areas.
Coal tar preparations should not be applied to patients with skin abrasion or skin that is inflamed, broken, or infected because exacerbation of the condition can occur and systemic absorption of the drug can be enhanced.
Sunlight (UV) exposure should be avoided for at least 24 hours following application of coal tar preparations, unless otherwise directed by a physician, because a photosensitivity reaction can occur. In addition, development of cutaneous viral infections is possible following UV light exposure.
Adequate studies in humans of the risks to the fetus have not been conducted. In one retrospective study in which pregnancy outcome data were gathered using a patient questionnaire among women with psoriasis or dermatitis, 19% of pregnancies without coal tar exposure (n = 59) resulted in spontaneous abortion and 5% in a congenital disorder compared to 26% of pregnancies with coal tar exposure (n = 23) resulting in spontaneous abortion and 4% in a congenital disorder. Until conclusive pregnancy outcome data become available, these agents should be used during pregnancy only when clearly needed. Coal tar preparations should only be considered for use during pregnancy when moisturizers and emollients are ineffective for symptom control. The effect of coal tar preparations during labor and delivery is unknown.
Manufacturer recommendations for breast-feeding mothers are not available. It is not known whether coal tar is distributed into breast milk and there is no information available on the effects of coal tar preparations on a nursing infant. Coal tar shampoos are generally compatible with use during breast-feeding, as most of the agent is rinsed off during bathing and skin contact time is low. Other coal tar skin preparations should be used with caution; alternatives recommended include general emollient and humectant lotions and baths. In one case of a mother applying coal tar ointment to her entire body except for face and breasts, the pyrene metabolite was detected in all urine samples of the nursing infant. Because the mother's breast milk contained no detectable pyrene and only low levels of the pyrene metabolite, the authors speculated that the infant obtained the pyrene via skin-to-skin or skin-to-mouth contact with the mother and metabolized it. If coal tar skin treatment is deemed necessary during lactation, the smallest amount of lotion, foam or oil possible should be used to treat the affected areas. The infant's skin should not come into direct contact with treated areas of the mother's skin. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally ingested drug, healthcare providers are encouraged to report the adverse effect to the FDA.
For the treatment of atopic dermatitis, dandruff, eczema, and seborrheic dermatitis:
Topical dosage (emulsion):
Adults: Apply topically to affected skin area(s) 1 to 4 times daily. May add 2 to 4 ounces to bath and soak for 10 to 20 minutes or 1 to 2 ounces to sink or basin and soak for 5 to minutes.
Topical dosage (foam):
Adults: Apply topically to the affected skin area(s) 1 to 4 times daily.
Topical dosage (shampoo):
Adults: Apply to wet hair and massage into lather at least twice weekly; leave on for several minutes, then rinse. Alternately, may apply topically to the psoriatic scalp area(s) at least twice weekly; wash off after 5 minutes, initially and gradually increase contact time up to 1 hour.
Topical dosage (ointment):
Adults: Apply topically to the affected skin area(s) 1 to 4 times daily.
For the treatment of psoriasis:
Topical dosage (emulsion):
Adults: Apply topically to affected skin area(s) 1 to 4 times daily. May add 2 to 4 ounces to bath and soak for 10 to 20 minutes or 1 to 2 ounces to sink or basin and soak for 5 to minutes. Guidelines recommend coal tar preparations for the treatment of mild to moderate psoriasis.
Infants*, Children*, and Adolescents*: Apply topically to the affected skin area(s) 3 times daily, or psoriatic scalp area(s) 2 to 3 times daily with daily shampoos to remove. Guidelines recommend coal tar preparations as monotherapy or combined with other topical therapies. Coal tar preparations in combination with phototherapy is effective for the treatment of psoriasis in children but may be limited by the theoretical long-term risk of carcinogenesis.
Topical dosage (foam):
Adults: Apply topically to the affected skin area(s) 1 to 4 times daily. Guidelines recommend coal tar preparations for the treatment of mild to moderate psoriasis.
Topical dosage (shampoo):
Adults: Apply to wet hair and massage into lather at least twice weekly; leave on for several minutes, then rinse. Alternately, may apply topically to the psoriatic scalp area(s) at least twice weekly; wash off after 5 minutes, initially and gradually increase contact time up to 1 hour. Guidelines recommend coal tar preparations for the treatment of mild to moderate psoriasis.
Topical dosage (suspension):
Adults: 1 to 3 capfuls added to bath and soak for 10 to 20 minutes. Guidelines recommend coal tar preparations for the treatment of mild to moderate psoriasis.
Topical dosage (ointment):
Adults: Apply topically to the affected skin area(s) 1 to 4 times daily. Guidelines recommend coal tar preparations for the treatment of mild to moderate psoriasis.
Maximum Dosage Limits:
-Adults
No maximum dosage information is available.
-Elderly
No maximum dosage information is available.
-Adolescents
No maximum dosage information is available.
-Children
No maximum dosage information is available.
Patients with Hepatic Impairment Dosing
No dosage adjustments are needed.
Patients with Renal Impairment Dosing
No dosage adjustments are needed.
*non-FDA-approved indication
There are no drug interactions associated with Coal Tar products.
The mechanism of action of coal tar is unclear, however, it is believed to aid in correcting the defect in keratinocyte differentiation in patients with psoriasis. A suggested mechanism involves suppression of deoxyribonucleic acid (DNA) synthesis and subsequent inhibition of keratinocyte proliferation. Coal tar exhibits keratoplastic and mild irritant activity. Coal tar may decrease the quantity and size of epidermal cells produced and inhibit mitosis, possibly through removal of oxygen in the skin. Shampoo and soap preparations may exert their action through absorption into the epidermis and enhancement of scale removal. It has been suggested that a reaction similar to that following exposure to sunlight can occur in the epidermis through interaction between the peroxides in coal tar and epidermal sulfhydryl groups. Subsequently, epidermal proliferation may be decreased. Coal tar preparations are also believed to possess antipruritic, antiseptic, astringent, antifungal, vasoconstrictive, and photosensitizing properties. Coal tar is reportedly carcinogenic in humans, inducing skin cancer primarily in the anogenital region, following prolonged exposure to coal tar in industrial settings. It is unlikely that patients treated acutely for dermatologic conditions are at an increased risk for developing skin cancer. Nevertheless, this risk should be considered during prolonged treatment periods.
Coal tar is applied topically. It is unknown if coal tar preparations pose a fetal risk or if they are distributed into breast milk.
-Route-Specific Pharmacokinetics
Topical Route
Coal tar is available in various formulations such as creams, gels, ointments, foam, bath preparations, shampoos, liquid preparations (lotions and emulsions), and cleansing bars and solutions. The location and type of lesion will determine the appropriate formulation to use.