DRUG RASH

Drug rash refers to skin reactions caused by medications, a common occurrence. In most cases, drug rashes resolve on their own once the responsible medication is discontinued. However, in a small percentage of patients (less than 2%), these rashes can lead to severe illness or even death.

Types of drug rash

Here are the explanations for drug-induced skin reactions:

• Disruption of normal skin function by certain drugs.
• Photosensitivity: Some medications can increase sensitivity to sunlight, leading to sunburn-like reactions and blister formation. These reactions are typically seen on exposed skin areas and show a clear boundary between covered and uncovered skin. Phototoxic reactions occur shortly after medication intake (within 5-15 hours) and usually resolve quickly upon stopping the medication. On the other hand, photoallergic reactions can cause eczema-like skin issues and develop gradually over weeks or months, with slower recovery upon medication cessation.
• Pigmentation changes: Drugs can induce various changes in skin pigmentation, including increased pigmentation (hyperpigmentation), decreased pigmentation (hypopigmentation), and alterations in skin color.

Drugs which worsen pre-existing skin diseases

Certain medications can worsen pre-existing skin conditions. Here are some common examples:

• Psoriasis can be exacerbated by medications like beta-blockers, lithium, antimalarial drugs, and ACE inhibitors.
• Eczema may worsen with the use of statins and diuretics.
• Acne can be aggravated by progesterone-only pills, steroids, cyclosporine, and some anti-epileptic drugs.
• Urticaria (hives) may worsen due to the use of NSAIDs, ACE inhibitors, or angiotensin receptor blockers (ARBs).

Common drug induced rahses

Drug-induced rashes can manifest in various ways:

• Exanthem: This is a widespread rash that presents with flat and raised red lesions, often accompanied by moderate to severe itching and burning. It typically appears within 7-10 days of starting certain medications such as antibiotics, antihypertensives, and lipid-lowering drugs.
• Urticarial/Angioedema-like Rash: This rash resembles raised red hives and may be itchy, with or without swelling of the lips and eyelids. In severe cases, it can lead to respiratory distress due to soft tissue swelling in the airway.
• Fixed Drug Eruption: This reaction results in round to oval-shaped red itchy patches of varying sizes on the skin and mucous membranes. These patches may leave behind post-inflammatory hyperpigmentation and tend to recur at the same site upon re-exposure to the triggering drug. Common culprits include antibiotics and NSAIDs.
• Drug-Induced Lupus: Certain medications can induce symptoms similar to systemic lupus erythematosus (SLE), including joint pain, rash, and fatigue. This is known as drug-induced lupus.
• Drug-Induced Vasculitis: Vasculitis caused by medications can lead to inflammation of blood vessels, resulting in skin lesions, joint pain, and sometimes organ involvement.
• Lichenoid Drug Eruption: This type of drug-induced rash resembles lichen planus and appears as flat-topped, purplish, itchy bumps on the skin.
• Erythema Nodosum: This condition involves painful, red nodules on the skin, often on the shins, and can be triggered by certain medications.

Treatment

Treating a drug rash hinges on the specific type of rash, its severity, and how quickly medical attention is sought after its onset. Identifying and discontinuing the responsible medication is paramount.

For mild rashes, topical steroids, moisturizers, soothing agents, and anti-itch medications are often effective. Moderate to severe rashes may require oral steroids, cyclosporine, intravenous immunoglobulins (IVIG), or biologic medications. Additional support for fever, skin erosions, and secondary infections might be necessary as well.