Can oral minoxidil be used in patients with allergy to topical minoxidil ?

Small study Suggests Oral Minoxidil Can be used in Patients with Topical Minoxidil Contact Allergy

Topical minoxidil is widely used in the treatment of female pattern hair loss. To date, it remains the only formally FDA and Health Canada approved treatment.

Skin Irritation can occur with topical minoxidil and is more common with minoxidil solution than the newer foam product. This is because the solution contains propylene glycol, a well known cause of irritation and sometimes contact allergy. The foam is devoid of propylene glycol. Rarely, patients can be allergic to the minoxidil component too.

Can patients who are allergic to topical minoxidil use oral minoxidil? According to a new study, the answer is yes.

Oral minoxidil is increasing used as an off label treatment for a variety of hair disorders. Doses used for treating hair loss range from 0.25 mg to 2.5 mg (or more) which are much lower doses than than the doses used in the past for treating high blood pressure (40 to 60 mg). . Side effects of oral minoxidil include shedding, hair growth on the face and body, hives, headaches, swelling in the feet/face and others.

See “10 Things You Need to Know about Oral Minoxidil for Hair Loss”

Therianou and colleagues recently reported 9 patients who demonstrated true patch test proven contact allergy to topical minoxidil but were able to tolerate oral minoxidil without any issues. Patients used oral minoxidil at low doses of 0.25 mg twice daily and follow up for these patients range from 7 to 33 months. None of the 9 patients reported side effects and all 9 patients were satisfied with results of their treatment.

Conclusion

The conclusion of this small study is that patients with patients with allergy to topical minoxidil may be able to use oral minoxidil at low doses without side effects. We don’t know if higher doses would cause problem and we don’t yet know the effects of treatments beyond 3 years. Presumably, the risk would be low.

Reference

Therianou et al. How Safe Is Prescribing Oral Minoxidil in Patients Allergic to Topical Minoxidil? Journal of the American Academy of Dermatology . 2020 Apr 11;S0190-9622(20)30567-3.