Derbac M Liquid - 150ml

Based on 16 reviews
In stock
Faye Bonnell - Medical Content Writer
Faye Bonnell
James O'Loan - CEO & Superintendent Pharmacist
James O'Loan
CEO & Superintendent Pharmacist
How we ensure accuracy in our content

What is Derbac M? 

Derbac M is an alcohol-free liquid emulsion containing the active ingredient Malathion, used for the treatment of head lice, pubic lice and their eggs, as well as scabies in adults and children aged 6 months and over. 

How to use this product

Always take Derbac M exactly as described in the patient information leaflet or as your doctor / Chemist4U pharmacist has told you. For the treatment of head lice, apply Derbac M to dry hair and ensure that no part of the scalp is left uncovered. Work into the hair and spread the liquid evenly from root to tip, leaving it to dry naturally in a warm but well-ventilated room. 

For the treatment of pubic lice, apply Derbac M to the entire skin surface and pay attention to all hairy areas including bears and moustaches. Avoid any other areas above the neck. Leave on for at least an hour before washing off, or preferably leave it on overnight. 

For the treatment of scabies, apply Derbac M to the entire skin surface. For children under the age of 2, apply the liquid to the scalp, face and ears, avoiding the eyes and mouth. This may not be necessary for adults. Do not wash or bathe for 24 hours - if you need to wash your hands, reapply Derbac M immediately. Repeat the treatment after 7 days. 

How does malathion treat head lice? 

The active ingredient in Derbac M is malathion, a medicine that belongs to a class of drugs known as organophosphates. These work by paralyzing and killing live lice that live on the human body and their eggs. 

What are head lice? 

Head lice are tiny insects that live among human hairs, feeding on blood from the scalp. Head lice are a very common problem in young, school-aged children and, while annoying, aren’t dangerous and don’t spread disease. The symptoms of head lice are itchiness and visible yellow, tan or brown dots in the hair. 

Is Derbac M suitable for children? 

Derbac M is suitable for children over the age of 6 months old. Do not use this product on infants less than 6 months old unless your doctor specifically tells you to. 

Is Derbac M suitable for pregnant or breastfeeding women? 

If you are pregnant or breastfeeding, think you may be pregnant or are planning to have a baby, you must ask your doctor or Chemist4U pharmacist for advice before taking any new medicine.

When should this product not be used? 

Derbac M may be unsuitable for certain people. Do not use this product on infants under the age of 6 months old, or if you are allergic to any of the ingredients. Talk to your doctor or Chemist4U pharmacist before taking this medicine if you have asthma. If you have sensitive skin, test the product on a small area of skin before use. Do not use this product more than once a week and for no more than 3 consecutive weeks. 

Are there any side effects? 

Like all medicines, Derbac M may cause side effects in some people, but these won’t affect everybody. Seek emergency medical attention if you notice any signs of a severe allergic reaction, symptoms of which include swelling of the face and throat, skin rash, breathing difficulties and/or loss of consciousness. Derbac M may cause skin irritation or chemical burns. If you experience any side effects, including any not included in the patient information leaflet, you can report them using the MHRA Yellow Card Scheme.

Storage information

Store below 25°C in a cool, dry place out of sight and reach of children. Do not use after the expiry date, referring to the last day of the month stated on the packaging.  Do not throw away any medicines via wastewater or household waste.

Important information

This product is a medicine; make sure to speak to your doctor or Chemist4U pharmacist before taking this product if you have an underlying medical problem or are taking any other medicine or complementary therapy. If your symptoms get worse or continue after taking this product, contact us or your doctor. For medical services in your area, please refer to

If you are pregnant, trying to become pregnant, or breastfeeding, speak to your doctor or our pharmacist before taking this product. If you suffer from any allergies, ask your doctor or our pharmacist if this medicine is right for you.

Store all medicines out of sight and reach of children.

Please read the included leaflet carefully before using this product.

Please contact your GP if appropriate regarding this product.

Helpful Advice on Medication Restrictions & Addiction

For further information on our medication restrictions policy, please click here.

If you are concerned about addiction to 'over the counter' medication, we urge you to visit the below links for professional help and advice:

NHS Help & Advice on Drug Addiction

Talk To Frank - Drug Addiction Help & Support


  • The active substance of Derbac M Liquid is Malathion. It contains 0.5% by weight. The other ingredients in Derbac M Liquid are methylhydroxybenzoate (E218), propylhydroxybenzoate (E216), emulsifying wax, potassium citrate, citric acid, perfume HT52 and water.

Drug Data
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What are nits and head lice?

Is your child itching away at their head like there’s no tomorrow? Are you tired of telling them to stop scratching their scalp?

Well don’t just assume that they’re being overly dramatic about a little itching, because they could be suffering with head lice!

Yes, those little lice could be making your head a home right now, so let’s take a look at what you can do to evict them before they invite all of their little lousy friends over for a party.

Read More

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Shipping Times

MethodHandling TimeTransit TimeTimescaleApprox Cost
Standard Shipping (3-5 Working Days)123£2.95
Royal Mail Tracked 24011£4.95

Times are given in working days and are approximate. Costs may change based on order total, day of the week or location within the UK. Ability to hit timescales will depend on whether the products are ordered before a cut off time, as well as additional administration time incurred in reviewing your order.

Please review the estimates at the checkout.

Shipping Costs

Free UK Delivery on all orders over £30* - Delivery within 3-5 working days.

Standard UK Delivery - £2.95* - Delivery within 3-5 working days.

Express UK Delivery - £4.95** - Delivery within 1-2 working days.

Temperature Controlled Delivery - £8.85 - Delivery within 1-3 working days.

Please Note: These prices are shown as a guide only. All delivery times are approximate but have been obtained in good faith.

*Excluding refrigerated products and treatments which are subject to different postage charges.


Discreet Delivery

All our items are sent completely discreet for your peace of mind.

This means the packaging is plain, there is no mention of what product is inside your package and there is no mention of Chemist4U either.

We respect that many of our products are of a sensitive nature - this is why we take every step to keep your purchases private.

Returns Information

Customers can read our full returns policy by clicking here

Derbac M Liquid - 150ml Reviews

Simon B,
This item works
Robert Turnham,
It does what it is supposed to do
Lindsey Steele,
Works well
Patrick Connolly,
Much less itching
Juan Carlos Mateo,
Easy to apply. It works and quickly resolves an unpleasant problem.