The irritation often referred to as a millipede “burn” is a chemical reaction caused by the animal’s defensive mechanism, not a thermal injury. When threatened, millipedes, which cannot bite or sting, excrete a caustic liquid from specialized glands called ozopores located along their bodies. This secretion is designed to repel predators, but accidental contact with human skin results in a painful, localized reaction. This article outlines the nature of this chemical irritant, the expected timeline for recovery, and the necessary immediate treatment steps.
Understanding the Millipede’s Defensive Secretion
The sensation of burning and visible skin changes result from a complex mixture of irritating chemicals released by the millipede. The primary components responsible for the skin reaction are often benzoquinones, which are caustic and can chemically damage or irritate skin and mucous membranes upon contact. The defensive fluid may also contain other potent chemicals, which vary by species, including hydrogen cyanide, hydrochloric acid, and phenols. Although the amount of these toxins is small and not systemically poisonous to humans, the localized concentration is sufficient to cause immediate symptoms.
Upon contact, the affected area typically exhibits immediate redness, a distinct stinging or burning sensation, and localized itching. A distinguishing feature of this exposure is the temporary but noticeable discoloration of the skin. The benzoquinones react with skin proteins, creating a brown, yellow, or sometimes purple stain that can resemble a mild chemical burn.
Expected Timeline and Immediate First Aid
The duration of a millipede “burn” depends on the concentration of the secretion, the millipede species, and how quickly the area is cleaned. For most minor exposures, the acute pain and burning sensation subside within a few hours. Localized redness and mild irritation, such as itching, may persist for a day or two. The most persistent symptom is skin discoloration, which may take several days to a few weeks to completely fade as the stained outer layer of skin naturally exfoliates.
Immediate treatment centers on physically removing the chemical irritant from the skin. The affected area should be thoroughly washed with soap and water for at least 15 to 20 minutes to dissolve and wash away the oily secretions. After decontamination, applying a mild topical corticosteroid cream, such as 1% hydrocortisone, three times daily can help reduce inflammation and itching. Any clothing that came into contact with the secretion should be washed immediately, as the quinones can also stain fabric.
When to Seek Medical Attention
While most millipede contact results in a self-limited, minor irritation, certain situations require professional medical assessment. The most serious concern is contact with sensitive areas, particularly the eyes. If the secretion gets into the eyes, immediate and prolonged irrigation with water for at least 20 minutes is mandatory, followed by urgent evaluation by an ophthalmologist, as eye exposure can lead to severe issues like corneal inflammation.
Medical attention is necessary if signs of a secondary infection develop in the affected area. These symptoms include increasing pain, warmth, spreading redness beyond the initial contact site, or the presence of pus or significant blistering. A healthcare provider should also be consulted if the pain, redness, or itching persists for longer than the expected timeline of a few days, or if symptoms are unusually severe. Finally, any signs of a systemic or severe allergic reaction—such as widespread rash, facial swelling, or difficulty breathing—warrant emergency medical care.