Scratching the itch: Crotamiton for scabies
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The bottom line
Crotamiton is a medication for scabies infestation. Crotamiton kills the scabies mites and helps with the intense itching associated with scabies. Although it is generally safe, side effects include skin irritation, a burning sensation, itching, and rash. While permethrin has taken the place of crotamiton as first-line therapy, crotamiton remains an option for the treatment of scabies.
Prevention tips
Keep crotamiton lotion up, away, and out of reach of children.
Follow package directions.
When crotamiton is prescribed for a child, an adult should apply it as prescribed by the doctor.
Do not swallow crotamiton.
Keep crotamiton away from eyes and other mucous membranes.
Do not use on severely inflamed skin.
This really happened
A 23-year-old woman drank an unknown amount of crotamiton 10% to harm herself. Her family attempted to induce vomiting with salt water (which is never recommended, and can actually cause more toxicity) and took her to the hospital. The medical team performed decontamination of her stomach, including gastric lavage (washing out the stomach, also called “stomach pumping”) and they gave her activated charcoal. Shortly thereafter, she had 3 tonic-clonic seizures. She was treated for the seizures and was sedated. She developed low blood pressure and abnormal muscle movements that were concerning for neurological damage. The results of her blood lab work were normal, and crotamiton was confirmed to be present in her blood. She made a full recovery and was discharged from the hospital 6 days later without any remaining issues (from Meredith et al., 1990).
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What is scabies?
Scabies occurs when the parasitic mite Sarcoptes scabiei infests the skin. It is very contagious and is spread through direct skin-to-skin contact as well as contact with infested bedding and clothing. Scabies mites are very small and have 8 legs, similar to spiders and ticks. Scabies causes intense itching which is worse at night and results in sores from scratching. A rash that looks like pimples is common where the mites burrow into the skin.
How does crotamiton work?
Crotamiton kills scabies mites. The exact way it works is unknown. It may disrupt nerve and muscle function in the mites, leading to paralysis and death of the mite. In the affected person, it also relieves itching by blocking histamine and serotonin, and by blocking the ion channels that send itch signals to the brain.
Worried about a crotamiton exposure?
If someone swallows crotamiton, gets it in the eyes or nose, or if you have a question about using crotamiton safely, use the webPOISONCONTROL® online tool to get help, or call your poison center at 1-800-222-1222. Whether online or by phone, expert guidance is always free, confidential, and available 24 hours a day.
Where is crotamiton found today?
Crotamiton comes as a 10% topical lotion and cream. Brand names include Crotan (US) and Eurax (UK and EU), but generics are also available. It is available by prescription only.
Using crotamiton safely
Follow the package directions. Crotamiton lotion is usually applied from the chin down to the soles of the feet. This first application should not be washed off. A second application is usually recommended 24 hours later. Wash off 48 hours after the second application. Be sure to put on freshly washed clothes and change bedding. For severe cases, another treatment may be needed after 1 week.
What are common side effects of crotamiton?
Side effects are usually mild and do not require medical attention. Users sometimes report a burning or stinging sensation in the areas where crotamiton is applied, localized skin irritation, itching, and rash. Allergic reactions (hives, difficulty breathing, swelling of the lips or throat, chest tightness) have also been reported. These serious reactions are rare.
What ingredients are often used alongside crotamiton?
Inactive ingredients (excipients) depend on the brand. The formulation available in the US contains several inactive ingredients such as purified water, mineral oil, lanolin, benzyl alcohol, cetyl and cetearyl alcohols, and propylene glycol. These ingredients have their own toxicities and can cause problems if too much is applied to the skin, especially in children. Benzyl alcohol can cause methemoglobinemia (a condition in which the blood cannot carry oxygen properly) if too much is applied or if it is applied too frequently.
Permethrin: A more effective alternative?
Permethrin is now the most used first-line treatment for scabies in the US. It is more effective than crotamiton in treating a scabies infestation and has a similar side effect profile. A 1% nonprescription formulation is used for lice. The 5% permethrin cream for scabies is a prescription medication.
While permethrin is usually the preferred treatment for scabies, crotamiton may be recommended for children under 2 months of age, when permethrin is unsuccessful, or for persistent itching. It is also less expensive than permethrin.
References
Arditti J, Jouglard J. Surdosage percutane de crotaminon et suspission de methemoglobinemie. Bull Med Leg Toxicol. 1978;21(5):661-2.
Meredith TJ, Dawling S, McNicol M. Crotamiton overdose [letter]. Hum Exp Toxicol. 1990 Jan;9(1):57.