A silicone-based head-lice lotion
Dimeticone
A silicone-based lotion used to treat head lice by physically coating and smothering them.
What is Dimeticone?
Dimeticone is a silicone-based lotion used to treat head lice. Instead of poisoning the lice like older insecticide treatments, it works physically by coating them in a layer that blocks their breathing and dries them out, which is why lice rarely become resistant to it. It is applied to dry hair, left on for the recommended time, then washed out, and usually a second application is needed about a week later to deal with newly hatched lice. It is flammable while in the hair, so flames, lit cigarettes and hair dryers must be kept well away until the hair is washed and dry. (Dimeticone is also used in some anti-foaming and infant-colic remedies, but the focus here is the head-lice treatment.)
Education and reference only. This is a plain-language guide to Dimeticone — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Dimeticone is a silicone-based liquid used as a head-lice treatment. It is one of the most commonly recommended treatments in the UK because it works by a physical action rather than as a chemical insecticide, so head lice do not easily become resistant to it. It is applied directly to the hair and scalp, left on for a set time, then washed out. The same ingredient is also found in some medicines for trapped wind and infant colic, where it acts as an anti-foaming agent, but here we are focusing on its main use against head lice.
How it works
When dimeticone is spread through the hair it coats the lice in a thin silicone layer. This blocks the tiny breathing holes the lice use and disrupts their ability to manage water, so they suffocate and dry out. Because this is a physical effect rather than a poison, lice cannot develop resistance to it in the way they can to older insecticide treatments. It does not reliably kill all the eggs, which is why a repeat application a week or so later is usually advised to catch lice that hatch after the first treatment.
Company & origin
Originated / developed by: Various manufacturers.
A widely used over-the-counter head-lice treatment in the UK that works physically rather than as an insecticide.
Practical use
How to take Dimeticone
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Apply it to dry hair, spreading it thoroughly so the whole scalp and all the hair, from roots to tips, is covered.
- Leave it on for the full recommended time before washing it out, rather than rinsing it off early.
- Keep it away from naked flames, lit cigarettes and hair dryers until the hair is washed and completely dry, as it is flammable.
- Repeat the treatment about a week later to catch any lice that hatch from eggs after the first application.
- Avoid getting it in the eyes, and check and treat other affected household members at the same time.
Weighing it up
Advantages & disadvantages of Dimeticone
Advantages
- Works by physically smothering lice, so they rarely become resistant to it.
- Available without a prescription and suitable for most people, including young children.
- Does not rely on insecticides, which appeals to many families.
Disadvantages
- It is flammable while in the hair, so flames and hair dryers must be kept well away.
- Usually needs a second application about a week later to be fully effective.
- Can sometimes irritate the skin or scalp, or sting if it gets into the eyes.
Practical use
Good to know
The most important safety point with dimeticone is that it is flammable while it is on the hair: keep away from naked flames, lit cigarettes, gas cookers and especially hair dryers until the treatment has been washed out and the hair is fully dry, because the silicone coating can catch fire. To work well it needs to be applied thoroughly so every part of the hair and scalp is covered, and left on for the full recommended time rather than rinsed off early. A single treatment often is not enough on its own, so a second application about a week later is usually needed to deal with lice that hatch from eggs the first treatment missed. It can sometimes irritate the skin or scalp, or sting the eyes if it gets into them. Checking the rest of the household with a detection comb and treating anyone affected at the same time helps stop the lice coming back.
Who should not take it / use with caution
- People who have had a reaction to dimeticone or any of the lotion's ingredients should not use it.
- It is used with care on broken, inflamed or infected scalp skin; ask a pharmacist for advice.
- Ask a pharmacist before using it on very young infants or if you are unsure it is suitable.
Monitoring
- Checking with a detection comb after treatment to confirm the lice have gone.
- Watching for any skin or scalp irritation where it has been applied.
- Reviewing whether a repeat application or a different approach is needed if lice remain.
Side effects
- Skin or scalp irritation, redness or itching where it is applied.
- Stinging or watering if it gets into the eyes.
- Rarely, a more troublesome skin reaction, which means it should be washed off and advice sought.
Key interactions
- There are no well-established interactions with medicines taken by mouth, as it works only on the hair and scalp.
- Avoid using it at the same time as other head-lice products unless advised, to prevent extra irritation.
- Its main practical hazard is flammability, not a drug interaction, so keep heat and flames away.
Available as: A lotion, spray or liquid applied to the hair and scalp.
Answers
Dimeticone: frequently asked questions
What is dimeticone used for?
Its main use is treating head lice, which it does by physically coating and smothering them rather than acting as an insecticide; the same ingredient is also used in some anti-foaming and colic remedies.
Why is it flammable?
The silicone coating it leaves on the hair can catch fire, so you must keep away from naked flames, lit cigarettes and hair dryers until the treatment is washed out and the hair is fully dry.
Why do I need to use it twice?
One application does not reliably kill all the eggs, so a second treatment about a week later is usually needed to deal with lice that hatch afterwards.
Do lice become resistant to it?
Because it works by physically smothering lice rather than poisoning them, lice rarely become resistant to it, unlike older insecticide treatments.
Can children use it?
It is suitable for most people, including young children, but ask a pharmacist before using it on very young infants or on broken or inflamed scalp skin.
The wider class
About Head-lice treatment (silicone-based)
Dimeticone belongs to the head-lice treatment (silicone-based) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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