Derbac M Liquid – 150ml

Description

Derbac M Liquid – 150ml

Derbac M Liquid is a treatment for head lice (pediculosis capitis) and their eggs (nits). It contains malathion 0.5%, an insecticide that kills head lice and their eggs on contact. It is applied to dry hair, left on for 12 hours, and then washed out.

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How It Works

Malathion is an organophosphorus insecticide that works by inhibiting the enzyme cholinesterase in head lice. This causes paralysis and death of the lice. It is also effective against lice eggs (nits), meaning a single application may be sufficient, though a second treatment after 7 days is recommended to ensure complete eradication.

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Directions for Use

Apply Derbac M to dry hair, rubbing it in thoroughly until the entire scalp and all hair is covered from root to tip. Leave on for at least 12 hours (overnight is ideal). Wash out with normal shampoo. While the hair is still wet, use a fine-toothed nit comb to remove dead lice and eggs. Repeat the treatment after 7 days if live lice are still found. If you are unsure how to use this product, speak to your PillSorted pharmacist.

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Active Ingredients

• Malathion 0.5% w/v in an aqueous base

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Possible Side Effects

• Scalp irritation, itching or redness (uncommon)
• Skin reactions in people with sensitive skin (rare)

If irritation persists or worsens, stop using the product and speak to your PillSorted pharmacist or doctor.

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Who Should Not Use This Product

• People with a known allergy to malathion or any other ingredient in the liquid
• Babies under 6 months of age (unless under medical supervision)
• Do not use if the scalp is severely broken, infected or inflamed

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Pregnancy and Breastfeeding

Derbac M may be used during pregnancy and breastfeeding if necessary, but speak to your doctor or PillSorted pharmacist before use to confirm suitability.

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Storage

Store below 25°C. Keep away from naked flames — this product is flammable. Keep out of sight and reach of children. Do not use after the expiry date shown on the packaging.

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Important Information

• This product is a medicine. Speak to your doctor or PillSorted pharmacist before taking this product if you have an underlying medical condition or are taking any other medication or complementary therapy.
• If symptoms worsen or persist, contact your doctor.
• If pregnant, trying to conceive or breastfeeding, seek medical advice before use.
• If you suffer from allergies, confirm suitability with your PillSorted pharmacist before use.
• Store out of sight and reach of children.
• Read the enclosed patient information leaflet carefully before use.
• Contact your GP where appropriate.

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Patient Information Leaflet

For the full Patient Information Leaflet (PIL) for this product, visit the electronic Medicines Compendium (EMC). For further information about head lice treatments, visit NHS.uk.

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This content has been medically reviewed and approved by Zeinab Ardeshir (GPhC 2075730), Superintendent Pharmacist at PillSorted (GPhC-registered online pharmacy 9011258). Last reviewed: March 2026.