The use of laundry sanitisers increased massively during the Covid pandemic in the thought that SARS-CoV-2 virus might be brought home on clothing. I know we definitely used it to wash my surgical scrubs, the garments that replaced my suits and dresses for work for a 2 year period. We still use laundry sanitisers now to wash teenage clothes that have that particular odour that only teenage clothes have or sports clothing which can be especially odorous or dirty. With two sons that play rugby, we actually go through quite a lot of the stuff!
It was interesting therefore to read a paper about a condition called hyperkeratotic flexural erythema which the authors thought was linked to the use of a compound called benzalkonium chloride (BAK) in laundry sanitisers.
[Dear K, Gan D, Stavrakoglou A et al. Hyperkeratotic flexural erythema (more commonly known as granular parakeratosis) with use of laundry sanitizers containing benzalkonium chloride. Clin Exp Dermatol 2022; 47:2196-2200.]
What is hyperkeratotic flexural erythema?
This is a relatively uncommon disorder which may also be called granular parakeratosis (GP). We don’t really know what causes it but is thought to be due to skin contact with some sort of chemical or organism combined with friction, sweating and occlusion.
It was originally thought to be due to a possible reaction to deodorants but the histology (analysis of a biopsy of affected skin) did not show the typical findings of contact dermatitis.
It was then thought to be linked to the use of benzalkonium chloride (BAK) in bath oils. Indeed the first case I saw was due to a child with eczema whose mum kept increasing the amount of benzalkonium chloride-containing bath oil as she thought his eczema kept on worsening. What in fact she saw was the development of hyperkeratotic flexural erythema.
It was then thought to be due a disruption of the skin microbiome as some cases responded to antibiotic therapy.
What did the study show?
The study was based in Victoria, Australia and 45 cases of GP were identified by 9 dermatologists over a 12 month period. Each patient was using a BAK-containing laundry santiser at the time of the rash.
What does the rash look like?
It typically presents as a symmetrical rash with a very characteristic reddish/brownish scaling or peeling. It usually occurs in flexural areas such as the groin or genital area or around the armpits or on the trunk. It may or may not be itchy. It might affect women more commonly but it can be reported in anyone. I see it a lot in kids.
What is benzalkonium chloride?
It is a quaternary ammonium compound which is used as an antiseptic and also as a preservative. It is commonly found in most domestic laundry sanitisers and also in certain emollients and soap substitutes prescribed in eczema especially when there is recurrent infection.
If I think I have it what should I do?
You should see your dermatologist as most family doctors will not have seen this condition. Swabs should be taken and if any organisms are found, they should be treated with antibiotics. We might need to do a skin biopsy. It is not an allergic reaction so patch testing or prick testing is not required.
Greasy emollients can help. If there is a lot of itch then a topical steroid may be of help. In my experience, cessation of the BAK-containing emollient is the only thing that really helps.
The authors recommend discontinuing the use of BAK-containing laundry sanitisers, cleaning the washing machine by running an empty wash and repeated washing and/or disposal of BAK-contaminated clothing.
Dr Sandy Flann, Consultant Dermatologist