Topical keratolytic / antipruritic Pregnancy: Inadequate evidence of safety in pregnant and lactating women, but coal tar preparations have been used for many years without apparent ill-consequence. Recommended to restrict use in pregnancy and lactation to intermittent use, low concentration, relatively small percentage of body surface, and avoid use during the first trimester.

Coal tar

Brand names: Exorex, Psoriderm, Polytar

Coal tar is a topical keratolytic and antipruritic preparation, available in various vehicles, used to treat chronic plaque psoriasis and, in some formulations, eczema and scalp conditions such as seborrhoeic dermatitis.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Apply a thin layer to the affected areas, two to three times per day

Route: Topical (cutaneous; Exorex lotion/emulsion)

Frequency: Two to three times per day

Adults and children over 12 years of age: ensure lesions are clean, apply a thin layer two to three times per day to affected areas, massage gently and leave to dry. For young children under 12 years of age and the elderly: the emulsion may be diluted by mixing with a few drops of freshly boiled and cooled water in the palm of the hand. Enhances photosensitivity — avoid direct sunlight after application; do not apply to genital/rectal areas; apply with caution to the face. Fire hazard — instruct patients not to smoke or go near naked flames. Source is the Exorex (coal tar) lotion SPC; dosing for other coal tar formulations is not covered here.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Presence of folliculitis and acne vulgaris
Disease characterised by photosensitivity such as lupus erythematosus or allergy to sunlight
Inflamed or broken skin (open exuding wounds or infection of the skin)

Side effects

Skin irritation
Photosensitivity of the skin
Acne-like eruptions of the skin
Increased risk of skin cancer reported in psoriatic patients treated with combination of coal tar and UVB radiation (epidemiological studies of coal tar alone inconclusive)

Interactions

None known

Clinical monograph

How it works

Coal tar has anti-inflammatory, antimitotic, antipruritic and antiscaling actions on the skin, helping to normalise the accelerated keratinocyte turnover characteristic of psoriasis, although its precise mechanism is not fully defined.

Prescribing in practice

Coal tar increases sensitivity to ultraviolet light, so treated skin should be protected from sunlight and caution is needed when it is combined with phototherapy to avoid burning.
It can cause skin irritation and folliculitis and should be avoided on broken, inflamed or infected skin and in acute or pustular psoriasis.
Preparations stain skin, hair, clothing and bathware, and have a characteristic odour.

Monitoring

No laboratory monitoring is required; review the skin for irritation, folliculitis and treatment response.

Counselling the patient

Apply as directed and wash your hands afterwards; expect staining of fabrics and a tar smell.
Protect treated skin from strong sunlight and tell your team if you are also having light therapy.
Stop if the skin becomes sore, spotty or irritated.

Evidence & guidelines

Coal tar is a long-established topical option for chronic plaque psoriasis and is recommended within NICE psoriasis guidance as part of stepped topical therapy.

Reference: NICE CG153; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Pathways