School has started again. That means homework, packing lunches, after school sports, and the crud. In the retail pharmacy world, we see a flood of prescriptions about 3-5 weeks after school starts; children come down with everything from ear infections, strep throat, and bronchitis, to head lice.  That may be why September is “Head Lice Prevention Month”.

The scenario starts by receiving the dreaded letter from the school nurse. A kid in your child’s class has lice. Duh, duh, duuuh. I remember that note coming home when I was in elementary school. My mom sat my little second grade, Food Allergy Pharmacist self on a dining room chair and began to explore hair and scalp. Maybe I have been slightly traumatized (thanks Mom), but I clearly remember my mother, who had never seen a louse before, totally FREAK OUT. I had lice (insert the “Imperial March” music aka Darth Vader’s theme song).  My head is itching just typing this post.

Don’t panic and don’t death march up to the pharmacy. Its okay. Not the end of the world.

keep calm and strike back

Yes, you will spend hours examining every single hair on your child’s head with the precision of a surgeon and the intensity of…well…Darth Vader.  (Confession: E has been on a Star Wars kick for a while now, he and my husband will be happy to see that I have been fully integrated. At this moment, my brain can only conjure Dark Side metaphors.)

Numerous methods have been employed to do away with lice including heat (not a light saber), combing, smothering or suffocating, pediculicides (aka bug killer), and more. I want to be clear that I am not going to promote one type of lice treatment over another in this post. I simply want to discuss OTC lice treatment options as they relate to food allergies. I will provide links to a number of resources; I encourage everyone to read the good, the bad, and the ugly of each option and decide for themselves. Please use caution with anything (including food items and oils) placed on the head especially for those with atopic dermatitis, eczema, and any other skin conditions. Some of the forums I reviewed listed combinations of products, long treatment durations, large quantities, and use of plastic bags and sleeping caps especially in children that I felt were potentially dangerous. I did not include those links based on my opinion of safety issues.

I feel that two paths to reaction may be possible while treating and dealing with head lice. These paths are tentative, hypothetical connections. The medical community has not found definitive data directly correlating food allergy to the lice treatments I will discuss. What I am trying to highlight is a potential for allergic reaction. I am making a logical leap based on the clinical knowledge we do have.

1. food sensitization via damaged skin

A recent article in the Journal of Allergy and Clinical Immunology  detailed a sensitization route where a food allergen applied topically to eczematous skin lead to subsequent anaphylaxis upon ingestion of the food. The researchers suggest that skin care be bland, avoiding use of sensitizing agents especially food. This is hypothesized pathway one.

“Natural” treatments have historically included food products such as olive oil, almond oil, mayonnaise, coconut oil and essential oils such as tea tree (melalueca), lavendar, eucalyptus, clove, cinnamon, and peppermint. I have also seen lotions and creams listed as alternatives to mayonnaise; keep in mind that lotions and creams may also contain food allergens e.g. Cetaphil contains nut oils. Several of the sites/forums I reviewed suggested using these “natural” treatments frequently, in some cases every other day. It was also suggested that various essential oils be used on a daily basis (spritzed onto hair or several drops placed in shampoo) as a preventative measure. Lice can be surprisingly resilient.

Never underestimate power of dark side

The article findings coupled with the suggested preventative measures of spritzing or shampooing hair daily with various food items has made me wonder whether similar sensitizations will or have taken place.

2. cross-reactivity due to similar structural features of the allergens

The second pathway (cross-reactivity) might be achieved through use of over-the-counter, OTC, lice treatments.  Some OTC products contain Pyrethrins (Brand names include: RID, PRONTO, Triple-X) which are naturally occurring extracts from the chrysanthemum flower. Permethrin (Brand name: NIX) is a synthetic pyrethroid; a product similar to pyrethrins. Use of either pyrethrins or permethrin in ragweed allergic individuals may cause breathing difficulties and “asthmatic episodes” according to package warnings of both pyrethrins and permethrin.  Allergic reactions have been seen in a few people who have used pyrethrins according to the ASTDR and the potential for contact dermatitis exists as well. Ragweed and chrysanthemums are members of the Asteraceae/Compositae plant family. Other plants in this family include: sunflower, safflower, artichoke, marigolds, and dandelions.

I have been reviewing numerous resources but have yet to find a concrete yes or no answer to my question: Will pyrethrins and permethrin cross-react to food items that are known to cause oral allergy syndrome (or Type 2 hypersensitivity reactions) with ragweed?

the force is strong with this one

Oral allergy syndrome has become common knowledge in the allergy community. It has been noted by the Asthma and Allergy Foundation of America that “ragweed cross-reacts with bananas and melons, so people with ragweed allergies may also react to honeydew, cantaloupe, and watermelons, or tomatoes. Zucchini, sunflower seeds, dandelions, chamomile tea, and Echinacea may also affect some people.”

In other words, if a person has a severe allergy to cantaloupe or tomato (as an example), will that person also react to a topical lice treatment containing permethrin or pyrethrin?

I don’t know the answer to this question but, seemingly, neither does anyone else (yet). Given the data known to be true at this time, I would use caution when selecting permethrin or pyrethrin  for lice eradication if you or your child have a severe allergy to any of the ragweed cross-reactive foods (even more so with concurrent asthma diagnoses).

For more information on diagnosing and treating head lice at home visit and the American Academy of Dermatology. It should also be noted that permethrin can be found in prescription scabies treatments, insect repellent directed to be used on gear and equipment, livestock insect repellent in the form of dust and spray, canine flea collars (permethrin is toxic to cats), and is listed on the World Health Organization’s Model List of Essential Medications Oct. 2013.

And remember , with lice “Do or do not.  There is no try.”


Images used are pieces of art for sale:




Asthma and Allergy Foundation of America: