Tretinoin/retin-A is a topical retinoid used for acne; a notable side effect is rebound inflammation.

• A. Hyperpigmentation
• B. Rebound inflammation
• C. Systemic hypertension
• D. Hair loss

Answer: (B)

Topical retinoids like tretinoin work by normalizing follicular keratinization and speeding epidermal turnover, which helps prevent clogged pores and acne formation. Because the skin is adapting to this change, irritation such as redness, dryness, and peeling is common early on. A notable side effect described with tretinoin is rebound inflammation—when the treatment is stopped abruptly or used inconsistently, the acne can temporarily flare as the skin readjusts its inflammatory balance. Hyperpigmentation is not a typical direct side effect of the drug (in fact, retinoids can help reduce pigmentary changes over time with proper sun protection); systemic hypertension and hair loss are not expected from a topical agent. So rebound inflammation best explains the described adverse effect.