Xerostomia as a Rare Adverse Effect of Low-Dose Oral Minoxidil: A Case Report with Recurrence After Re-Challenge

This case report highlights xerostomia (dry mouth) as a rare adverse effect of low-dose oral minoxidil, a medication increasingly used by dermatologists for androgenetic alopecia. The patient experienced severe xerostomia, which recurred upon re-challenge with the drug, suggesting a systemic mechanism possibly involving autonomic dysregulation. Despite being a known antihypertensive, minoxidil's use in dermatology is rising, and this side effect has not been previously documented. The patient's symptoms resolved upon discontinuation of oral minoxidil and did not recur with topical use, indicating a potential systemic effect. Clinicians should consider this rare side effect, especially in patients with predispositions to salivary gland dysfunction, and may opt for topical formulations as a safer alternative.