• Kills mites lice and eggs effectively
  • Alternative to permethrin-based treatments
  • Prevents reinfestation with full contact treatment

How it works?

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Overview

Struggling with relentless itching caused by scabies or head lice? Derbac-M Lotion is a clinically proven treatment that kills both mites and lice - along with their eggs - to restore comfort and stop the cycle of re-infestation.
Its fast-acting formula targets the parasites directly on the skin and scalp, offering a trusted alternative when permethrin-based creams (like Lyclear) aren’t suitable.

This treatment requires a secure online consultation with a UK-registered prescriber and will only be supplied if clinically appropriate.


What is Derbac-M Lotion


Derbac-M Lotion contains malathion 0.5%, an insecticidal and antiparasitic medicine that works by disrupting the nervous system of mites and lice, killing both the adult parasites and their eggs (nits).
It is used to treat:

  • Scabies (Sarcoptes scabiei) – a contagious skin infestation that causes severe itching and rash.
  • Head lice and pubic lice – when other treatments have failed or aren’t tolerated.


Derbac-M is especially effective when permethrin isn’t suitable due to allergy or resistance. It can be safely used on both the skin and scalp, and is suitable for adults and children over 6 months old.

Because it destroys mites, lice, and eggs in one application, it helps prevent reinfestation when all contacts are treated together.

Directions

Follow your prescriber’s instructions carefully.

For Scabies:

  1. Apply the lotion evenly over the entire body from the neck down, paying special attention to folds of skin, under nails, between fingers and toes, and the soles of the feet.
  2. In infants and elderly people, also treat the face, ears, and scalp, avoiding eyes and mouth.
  3. Leave on for 24 hours, then wash off thoroughly and change into clean clothes.
  4. Reapply after 7 days to kill any newly hatched mites.
  5. Wash bedding, clothing, and towels at 60°C after each application.


For Head or Pubic Lice:

  1. Apply the lotion to dry hair or affected area, ensuring full coverage of scalp and roots.
  2. Leave for 12 hours (overnight), then rinse and comb to remove dead lice and eggs.
  3. Repeat after 7 days if necessary.


Always treat all close contacts at the same time to prevent reinfection.

Side Effects

Most people tolerate Derbac-M well. Side effects, if they occur, are usually mild and short-lived.

Common (may affect up to 1 in 10 people):

  • Mild skin irritation or redness
  • Itching or tingling after application
  • Dryness or slight stinging on sensitive skin


Less common (may affect up to 1 in 100 people):

  • Flaking or temporary rash
  • Burning sensation or mild swelling at the application site


Rare but serious (seek urgent medical advice):

  • Severe allergic reaction (rash, swelling, difficulty breathing)
  • Widespread redness, blistering, or intense itching that worsens after use


Disclaimer: This is not a full list of side effects. Always read the patient information leaflet before use. If you notice anything unusual or concerning, stop using Derbac-M and speak to your doctor or pharmacist. In an emergency, call 999 or go to A&E.

Warnings

Do not use Derbac-M Lotion if you:

  • Are allergic to malathion or any other ingredients in the product
  • Have broken, inflamed, or infected skin
  • Are applying near the eyes or mucous membranes


Use with caution if you:

  • Are pregnant or breastfeeding – your prescriber will advise if suitable
  • Have asthma or breathing difficulties, as the vapour may irritate the lungs


Avoid flames, lit cigarettes, or heat sources during application and while the lotion is on the skin - Derbac-M is flammable.


For external use only.

Frequently asked questions

  • What is Derbac-M Liquid and how does it work?

    Derbac-M is a malathion-based liquid used to treat head lice, pubic lice and scabies. It works by disrupting the nervous system of the parasites, killing them over several hours. The liquid is left on the skin or hair for the recommended time before washing off. A repeated application is often needed to ensure complete clearance.

  • How do I apply Derbac-M for head lice?

    Apply Derbac-M to dry hair, ensuring full coverage of the scalp and roots. Leave it on for the time stated in the instructions, then wash out thoroughly. Combing with a fine-toothed nit comb removes dead lice and eggs. A second application after seven days is usually required to kill newly hatched lice.

  • Can Derbac-M be used to treat scabies?

    Yes. Derbac-M is licensed as an alternative treatment for scabies when first-line treatments such as permethrin are unsuitable. It must be applied over the entire body from the neck down and left for the recommended duration. All close contacts must also be treated to prevent reinfestation.

  • How long does Derbac-M take to work?

    Derbac-M begins killing parasites shortly after application, but full clearance often requires two treatments spaced seven days apart. Itching may continue for a short time as the skin recovers, especially after scabies treatment. This does not usually mean treatment failure. Seek advice if symptoms persist.

  • Is Derbac-M safe for children?

    Derbac-M can be used in children, but age-related restrictions apply depending on the condition being treated. Care must be taken to avoid the eyes and mouth, and supervision is essential. Always follow the instructions carefully or seek advice if unsure about suitability for your child.

  • What are the common side effects of Derbac-M?

    Mild stinging, dryness, irritation or a burning sensation on the skin or scalp can occur. These reactions are usually short-lived. If the area becomes very red, swollen or sore, or if you experience signs of allergy, stop using the product and seek medical advice.

  • Can I use Derbac-M if I am pregnant or breastfeeding?

    Derbac-M should only be used in pregnancy or breastfeeding if recommended by a clinician. Alternative treatments may be preferable depending on the condition being treated.Your clinician will help confirm the safest option.

  • How do I use Derbac-M for treating pubic lice (crabs)?

    Apply Derbac-M thoroughly to the affected area and surrounding skin, ensuring full coverage of hair shafts. Leave it on for the stated time before washing off. Clothing, bedding and towels should be washed at high temperatures to prevent reinfestation. A second application after seven days is usually required.

  • Can Derbac-M be used on the face or eyelashes?

    Derbac-M should not be used on eyelashes because of the risk of eye irritation. Eyelash lice require specialist treatment recommended by a clinician. For facial areas, only use Derbac-M if specifically advised, taking great care to avoid the eyes.

  • Do I need to wash bedding and clothing after using Derbac-M?

    Yes. Wash bedding, towels and recently worn clothing at 50-60°C to kill lice or mites. Items that cannot be washed should be sealed in a plastic bag for at least 72 hours. Cleaning combs and brushes is also important to avoid reinfestation of scabies. 

  • How do I treat my household if one person needs Derbac-M?

    For head lice, only people who are confirmed to be infected need treatment. For scabies, everyone in the same household or sexual partners must be treated at the same time, even if they have no symptoms. This prevents the infestation circulating.

  • Can Derbac-M cause hair dryness or scalp irritation?

    Some people notice dryness, itchiness or mild irritation after using Derbac-M on the scalp. Using a gentle, fragrance-free conditioner afterwards can help. If irritation becomes persistent or severe, stop using the product and seek advice for alternative treatments.

  • What should I do if Derbac-M doesn’t clear the infestation?

    If symptoms continue after two correctly spaced applications, reinfestation or incorrect usage is the most likely cause. Check all close contacts, treat them if needed and wash household items. If lice remain, a clinician may recommend an alternative treatment.

  • Can I swim, exercise or wash my hair while Derbac-M is on?

    No. Derbac-M must remain on the skin or scalp for the full recommended contact time without washing, sweating heavily or swimming. This ensures the product stays active long enough to work effectively. Wash off only after the stated time has passed.

  • Can Derbac-M be used alongside other lice treatments?

    In most cases, Derbac-M should be used as the only treatment during a course. Mixing products can irritate the skin and reduce effectiveness. If a previous product failed, wait before switching and follow the new instructions exactly. Seek advice if you are unsure.

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