Potassium permanganate (KMnO4) is an astringent with oxidizing and antiseptic properties, which dates from the 17th century and has been in medical use since the early 1800s. It is available as an over‐the‐counter preparation and is often used as compresses and baths for various exudative dermatoses. Its advantages include lower cost, good healing rate and reduced allergenic potential. However, it can stain skin (as well as clothing and ceramics), and more serious adverse effects include chemical burns and systemic toxicity. Owing to its easy availability, there is a risk of accidental or deliberate ingestion of this drug. The focus of this article is to increase awareness among dermatologists about the clinical use and adverse effects of KMnO4, as well as the signs and management of systemic toxicity.