Xerostomia as a Rare Adverse Effect of Low-Dose Oral Minoxidil: A Case Report With Recurrence After Rechallenge

Oral minoxidil, used for treating hair loss, can cause xerostomia (dry mouth) as a rare side effect, as demonstrated in a 74-year-old woman. Her symptoms resolved after stopping the medication and recurred upon reexposure, indicating a causal relationship. This case highlights the need for clinicians to consider dry mouth as a potential systemic reaction to oral minoxidil, even at low doses. The patient successfully switched to topical minoxidil without experiencing xerostomia again, suggesting that topical formulations may be a safer alternative for those predisposed to salivary gland dysfunction.