Fixed Drug Eruption

Clinical Description

An adverse cutaneous drug reaction that recurs at the same site with repeated exposure to the same agent though new areas may be involved in subsequent attacks.

Signs and Symptoms

• Itching and/or pain on affected area
• Typically, round sharply demarcated red-brown patch or plaque
• Occasionally may be bullous
• Later becomes darker
• Lesions can be found anywhere on the body but favours the lips, face, hands, feet and genitalia

Investigations

• Clinical and in relation to history

Drugs most frequently associated with FDE

• Sulphonamides
• NSAIDS
• Tetracyclines
• Barbiturates
• Carbamazepine
• Stop the offending medicine

Treatment

• Avoid triggering agent
• Use potent topical steroids e.g., Betamethasone 0.05% cream 12 hourly

If severe:

• Give Chlorpheniramine 4-8mg PO 12 hourly for 7 -14 days 18.4. URTICARIA

Clinical Description

A very itchy skin disease characterized by pruritic wheals or hives. It is due to extravasation of fluid in the upper dermis. It is called angioedema if deep dermis and subcutaneous tissues are involved leading to massive swelling.

Classification of urticaria

• Idiopathic
• Can be acute: having symptoms lasting up to 6 weeks
• Chronic: having symptoms lasting beyond 6 weeks
• Physical
• Urticaria that occur secondary to and external trigger e.g., heat, cold, pressure

Note: Identifying a specific cause of urticaria is usually a challenge and often a futile task.

Empirical treatment is encouraged in all cases

Signs and Symptoms

• Wheals are the hall mark of the disease
• Extreme pruritus but no excoriations are seen
• Transitory nature with individual lesions lasting 1–24 hours

Investigations

• Explain the condition to the patient
• Remove the cause if known
• Desist from giving medications for the duration of symptoms only and stopping immediately after they disappear.
• Give antihistamines for a set period as outlined below:
• Give Promethazine 25mg orally at night till 2 weeks after submission of the wheals.
• In so doing, antihistamines may need to be given for several months to effectively control the disease.
• Alternatively
• Give Chlorpheniramine 4-8mg at night or 8 hourly until two weeks after eruption of wheals.
• Give (alternatively) Cetirizine 5-10mg daily until two weeks after lesions clear.
• Apply Calamine lotion at night or 12 hourly

For tracheal angioedema

• Give Adrenaline 0.5mg stat dose sub- cutaneously in severe urticaria with tracheal angioedema

Red Flags

• If it is angioedema, refer.