Enlarged lymph nodes: A rare side effect of minoxidil

Minoxidil Induced Lymphadenopathy

Authors of a new report described a 23 year old male who presents for medical attention with concerns about a red, scaly itchy scalp accompanied by cervical lymphadenopathy. There were no signs of infections and a proper evaluation found to clear internal cause for the lymphadenopathy.

His history was remarkable for starting topical minoxidil solution 3 months prior. Lymphadenopathy started within days of using minoxidil. Every time he stopped and restarted the minoxidil the lymphadenopathy would return.

Patch testing was performed with both minoxidil and propylene glycol and the patient patch tested positive to minoxidil but not propylene glycol

All in all the conclusion was that the patient had an allergic contact dermatitis to minoxidil. The lymphadenopathy resolved permanent with cessation of minoxidil.

Comments

This is an interesting case and reminds us first that minoxidil can cause many red scalp issues including irritant contact dermatitis, allergic contact dermatitis and exacerbation of seborrheic dermatitis.

About 5.7% of the patients using the 5% liquid formulation and in 1.9% of the patients using the 2% formulation get application site reactions.

The foam can also cause allergic and irritant reactions. The ROGAINE FOAM 5% contain ethanol (alcohol) which can cause irritation. It also contain butylated hydroxytoluene, cetyl alcohol, and stearyl alcohol. Butylated hydroxytoluene may cause local skin reactions (e.g. contact dermatitis), or irritation to the eyes or mucous membranes. Cetyl alcohol and stearyl alcohol may cause local skin reactions (e.g. contact dermatitis). Studies of Rogaine foam showed that itching and rash occur in around 1 % of individuals.

Allergic Contact Dermatitis to Topical Minoxidil

Minoxidil is felt to be an important sensitizer and patients can develop minoxidil allergy after a long time of use - it does not necesarily happen quickly!

Allergic contact dermatitis to minoxidil is well recognized and the first such cases goes back to 1984 when a patient using minoxidil for alopecia areata developed allergic contact dermatitis.

Allergy to minoxidil can range from no scalp reaction, to scaly scalp to red itchy neck to rashes and swelling around the eyes to facial edema mimicking angioedema.

Patch testing with patches placed on the back can help differentiate many cases of true allergic contact dermatitis when testing is done with pure minoxidil as well as to the other ingredients in the formulation such as propylene glycol (if the original minoxidil contained propylene glycol). Some authors propose that photopatch testing should also be done. A patient with a positive test result to an ingredient like propylene glycol or some other solvent will be able to continue minoxiidl provided some other substitute is found. If the patient is truly allergic to the minoxidil ingredient, topical minoxidil should be stopped.

REFERENCE

Feryel A et al. Unusual clinical presentation of allergic contact dermatitis to topical minoxidil. Contact Dermatitis. 2022 Mar 28.

Weiss et al. Alopecia areata treated with topical minoxidil. Arch Dermatol. 1984;120:457–463.