Ingredient review
Bioresmethrin
INCI: BIORESMETHRIN
Bioresmethrin is a synthetic insecticide rarely used in skincare; it may be found in anti-lice or insect repellent products but is not a typical cosmetic ingredient.
In plain English
Bioresmethrin is a man-made chemical that kills insects. It is sometimes added to personal care products like shampoos or lotions meant to treat head lice or repel bugs. It is not a moisturizer or skin treatment, and it is not commonly found in everyday skincare. Because it is an insecticide, it can cause skin irritation in some people, especially with repeated use.
Review score
Safety, usefulness, and evidence
Higher-caution ingredient
The evidence base is still emerging, so marketing claims deserve extra caution.
Main practical flags: irritation is moderate; clogging risk is low.
- Source
- synthetic
- Evidence
- emerging
- Irritation
- moderate
- Clogging risk
- low
Quick decision guide
Read the cautions before using
Bioresmethrin can be useful, but watch for some irritation potential.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Bioresmethrin.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
moderateCan bother some users, especially with frequent use, damaged skin, or strong companion ingredients.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
emergingThe ingredient may be promising, but claims should be treated more cautiously.
What it is
Bioresmethrin is a synthetic pyrethroid insecticide, chemically related to natural pyrethrins found in chrysanthemum flowers. It is designed to target the nervous system of insects, making it effective against lice and other pests.
How it works
In a cosmetic product, bioresmethrin works by disrupting the nervous system of insects on contact, killing or repelling them. It does not provide any moisturizing, anti-aging, or skin-soothing benefits.
Pros
Effective against lice
Bioresmethrin is a potent insecticide that can quickly kill head lice and other parasites, making it useful in medicated shampoos.
Fast-acting
It works rapidly on contact, reducing the time needed for treatment compared to some natural alternatives.
Cons and cautions
Skin irritation risk
As a synthetic insecticide, bioresmethrin can cause redness, itching, or burning on the scalp or skin, especially with frequent use.
Not for daily skincare
This ingredient is not designed for moisturizing or anti-aging; using it in routine skincare could lead to unnecessary irritation.
Best for
- People treating head lice under medical guidance
- Individuals using insect repellent products in high-risk areas
Use caution if
- Anyone with sensitive skin or eczema
- Pregnant or nursing women (consult doctor first)
- Children under 2 years old (unless directed by a pediatrician)
Usage tips
Safety summary
Bioresmethrin is considered safe for occasional, short-term use as an insecticide in personal care products when used as directed. However, it can cause skin irritation and is not intended for daily skincare. Long-term safety data for cosmetic use is limited.
Research notes
Research on bioresmethrin focuses on its insecticidal properties and safety as a pesticide. There is limited peer-reviewed evidence on its use in cosmetics, and most studies are from regulatory agencies assessing its toxicity.
Common label clues
- Typical concentration
- Very low (typically under 0.1%)
- Regulatory status
- Approved for use as an insecticide in some countries, but not generally recognized as a cosmetic ingredient by the FDA or EU CosIng database. Use in cosmetics is limited and may require specific labeling.
- Common uses
- Anti-lice treatments, Insect repellent products
- Environmental note
- Synthetic pyrethroids like bioresmethrin can be toxic to aquatic life and should be disposed of properly, not washed down drains in large quantities.
Good to know
- Bioresmethrin is rarely found in standard skincare products; it is more common in medicated anti-lice treatments
- Always patch test before first use, even on the scalp
Common questions
What is Bioresmethrin in beauty products?
Bioresmethrin is a man-made chemical that kills insects. It is sometimes added to personal care products like shampoos or lotions meant to treat head lice or repel bugs. It is not a moisturizer or skin treatment, and it is not commonly found in everyday skincare. Because it is an insecticide, it can cause skin irritation in some people, especially with repeated use.
What does Bioresmethrin do in a beauty product?
In a cosmetic product, bioresmethrin works by disrupting the nervous system of insects on contact, killing or repelling them. It does not provide any moisturizing, anti-aging, or skin-soothing benefits.
Is Bioresmethrin safe for most people?
Bioresmethrin is considered safe for occasional, short-term use as an insecticide in personal care products when used as directed. However, it can cause skin irritation and is not intended for daily skincare. Long-term safety data for cosmetic use is limited.
Who should be careful with Bioresmethrin?
Anyone with sensitive skin or eczema Pregnant or nursing women (consult doctor first) Children under 2 years old (unless directed by a pediatrician)
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.