Description

Treatment for Head Lice and Their Eggs

Derbac M Liquid Overview

Derbac M Liquid is a medicated head lice treatment used to eliminate head lice (Pediculus humanus capitis) and their eggs (nits). It contains malathion 0.5%, an insecticide that works by disrupting the nervous system of lice, leading to their death.

In the UK, Derbac M is an over-the-counter pharmacy medicine (P) and is intended for short-term treatment of active head lice infestations following pharmacist advice.

Understanding Head Lice Infestation

What are head lice?

Head lice are small, wingless insects that live on the scalp and feed on blood. They are most common in children of school age but can affect anyone. Head lice spread through direct head-to-head contact, not through poor hygiene.

Common symptoms

Many people have no symptoms initially. When symptoms occur, they often include itching of the scalp, a tickling sensation, and irritation behind the ears or at the nape of the neck. Nits may be visible attached to hair shafts close to the scalp.

What Is Derbac M Liquid?

Derbac M contains malathion, an organophosphate insecticide that has been used for many years in the treatment of head lice. It is effective against both live lice and eggs, which helps reduce the risk of reinfestation when used correctly.

The liquid formulation is applied directly to dry hair and scalp.

How Does Derbac M Work?

Insecticidal action

Malathion works by inhibiting acetylcholinesterase, an enzyme essential for normal nerve function in insects. This causes paralysis and death of head lice.

Activity against eggs

Unlike some physical treatments, malathion also has ovicidal activity, meaning it can kill lice eggs as well as adult lice.

What Derbac M Treats — and What It Does Not

What it treats

Derbac M Liquid is used to treat:

• head lice infestations
• lice eggs (nits) attached to hair

What it does not treat

Derbac M does not:

• prevent reinfestation
• treat itching caused by other scalp conditions
• treat pubic or body lice

Ongoing itching after treatment does not necessarily mean treatment failure.

Who Is Derbac M Liquid For?

Derbac M may be suitable for:

• adults and children aged 6 months and over
• people with confirmed head lice infestation
• short-term treatment use only

Pharmacist assessment is required before supply.

Who Should Avoid Derbac M

Derbac M may not be suitable if:

• you are allergic to malathion or any ingredients
• the scalp is broken, inflamed, or infected
• you have asthma or other breathing problems (due to vapour sensitivity)
• the infestation is recurrent despite treatment

Medical advice should be sought if unsure.

How to Use Derbac M Liquid

Application guidance

• Apply to dry hair, ensuring the scalp and all hair are fully covered
• Allow to dry naturally and leave on for 12 hours
• Wash out with normal shampoo
• Repeat treatment after 7 days to ensure complete eradication

Always follow the instructions provided with the product.

Practical usage advice

• Use in a well-ventilated area
• Avoid naked flames or heat sources (product is flammable)
• Check all household members for lice and treat if necessary
• Use a fine-toothed comb to remove dead lice and nits

Safety, Warnings and Side Effects

Derbac M is generally effective when used correctly.

Some people may experience:

• scalp irritation or stinging
• strong smell during application

If severe irritation or breathing difficulty occurs, discontinue use and seek advice.

When to Seek Medical Advice

Speak to a GP or pharmacist if:

• treatment does not work after two applications
• infestation keeps returning
• the scalp becomes inflamed or infected
• there is uncertainty about diagnosis

Alternative treatments may be required.

Use in Pregnancy and Breastfeeding

Derbac M should be used during pregnancy or breastfeeding only on professional advice, as alternative physical treatments may be preferred.

How Derbac M Compares to Other Head Lice Treatments

Derbac M vs physical treatments

Physical treatments work by coating or dehydrating lice. Derbac M uses a chemical insecticide and may be effective where resistance to physical treatments is suspected.

Derbac M vs wet combing

Wet combing can be effective but requires repeated sessions. Derbac M offers a medicated alternative with ovicidal activity.

Supporting Lice Management

Regular detection combing, avoiding head-to-head contact during outbreaks, and treating all confirmed cases at the same time can help prevent reinfestation.

Derbac M Liquid Summary

Derbac M Liquid provides effective treatment for head lice and their eggs using malathion 0.5%. When applied correctly and repeated after seven days, it helps clear infestation and reduce the risk of reinfestation.

Persistent or recurrent infestations should always be reviewed by a healthcare professional.