Internal medical treatment of skin diseases — expanded notes
Treatment selection
Before systemic treatment, confirm diagnosis, severity and treatment goals. Record body surface area, special-site involvement, symptoms, quality-of-life impact and previous therapies. Review pregnancy potential, comorbidities, infection history, vaccination status, allergies, concomitant medicines and baseline laboratory results.
Systemic corticosteroids
Glucocorticoids bind intracellular receptors and alter transcription of inflammatory genes, reducing cytokines, leukocyte migration and immune activation. Adverse effects include hyperglycaemia, hypertension, mood changes, infection, osteoporosis, myopathy, cataracts, glaucoma, adrenal suppression and skin atrophy. Use a defined indication and plan; prolonged therapy requires tapering and risk mitigation. Systemic steroids are generally avoided as routine long-term psoriasis treatment because withdrawal can provoke severe rebound.
Conventional immunosuppressants
Retinoids
Isotretinoin reduces sebaceous gland size and sebum production, normalises follicular keratinisation and reduces inflammation. It is used for severe acne. Cheilitis and xerosis are common; monitor lipids and liver enzymes when indicated. It is highly teratogenic and requires strict pregnancy prevention. Acitretin is used in psoriasis and keratinisation disorders; it is also highly teratogenic and has prolonged reproductive precautions.
Biologics and targeted therapy
Biologics target defined cytokines or receptors, including TNF, IL-17, IL-23 and IL-4/IL-13 pathways. Before treatment, screen for latent tuberculosis and viral hepatitis according to the drug and local protocol, review vaccination status and assess active infection. JAK inhibitors require careful risk assessment because of serious infection, herpes zoster, thrombosis, cardiovascular events and malignancy warnings in selected populations.
Antimicrobials and other agents
- Dapsone: used in dermatitis herpetiformis and neutrophilic dermatoses; check G6PD and monitor blood count, haemolysis and methaemoglobinaemia.
- Antibiotics: choose according to organism, site, severity and local resistance; avoid unnecessary prolonged courses.
- Antifungals: terbinafine and azoles require review of liver disease and drug interactions.
- Antivirals: aciclovir/valaciclovir for herpes infections; adjust for renal impairment.
- Antihistamines: second-generation H1 blockers are generally preferred for itch/urticaria due to less sedation.
Safety monitoring
Baseline and follow-up tests depend on the medicine and may include CBC, liver and renal function, blood pressure, lipids, pregnancy testing, TB/hepatitis screening and eye examinations. Counsel patients about infection symptoms, drug interactions, sun protection and adherence.