TLDR Minoxidil can cause allergic skin reactions in some users.
In the document, a case of allergic contact dermatitis from the use of a 2% minoxidil solution is reported. A 22-year-old male with androgenic alopecia developed symptoms including burning, pruritus, and red papules and vesicles on his scalp, neck, and eyebrows after using the solution for 3 weeks. Patch testing showed a negative response to the standard series but a positive reaction to the minoxidil lotion. Five control subjects tested negative with the same lotion. The document suggests that while minoxidil's sensitizing potential is low, its increasing use for various types of alopecia may lead to more cases of allergic contact dermatitis. The document also briefly mentions allergic contact dermatitis from a Chinese herbal preparation named Yunnan Paiyao, but the main focus is on the minoxidil case.
29 citations,
August 1985 in “Contact Dermatitis” Minoxidil can cause allergic reactions like burning, itching, and red bumps.
[object Object] 
20 citations,
February 1985 in “Archives of Dermatology” Minoxidil helps hair regrowth, especially with more indeterminate hairs.
55 citations,
February 1985 in “Archives of Dermatology” Using minoxidil on the scalp can help grow hair for people with hereditary baldness.
80 citations,
September 1984 in “Journal of The American Academy of Dermatology” 5% minoxidil helps hair regrowth in androgenic alopecia.
78 citations,
April 1984 in “Archives of Dermatology” Minoxidil can help regrow hair in alopecia areata patients.
80 citations,
October 1983 in “BMJ” Minoxidil helps hair regrowth in alopecia patients, with 16 having good results and no side effects.
[object Object] 
56 citations,
August 1981 in “Journal of The American Academy of Dermatology” Minoxidil helps hair regrowth in alopecia areata safely.
January 2014 in “DOAJ (DOAJ: Directory of Open Access Journals)” Minoxidil can effectively treat patchy hair loss by stimulating hair growth.
[object Object]
