Doctors linked the case to minocycline, a prescription drug used for rosacea, acne and bacterial infections.
NEW YORK — A 68-year-old woman developed blue-gray patches on her arms, legs and tongue after taking minocycline for rosacea, according to a medical case report that drew renewed attention this week to a known but unusual drug reaction.
The case matters now because the skin changes appeared quickly, only weeks after the woman began a daily 100 mg dose of the antibiotic. Minocycline has been used for decades and is commonly prescribed for inflammatory skin problems and some infections, but doctors said the timing and spread of the discoloration made the case notable.
The woman, who was not publicly named, sought care after six weeks of dark patches on the skin of her arms and legs. The patches first appeared on her legs, then spread to her forearms. Doctors also found blue-gray discoloration along the sides of her tongue. The woman had rosacea, a chronic inflammatory skin condition that can cause redness, flushing and acne-like bumps on the face. Two weeks before the patches began, she had started oral minocycline, a tetracycline antibiotic often used to reduce inflammatory lesions linked to rosacea.
Doctors diagnosed her with minocycline-induced hyperpigmentation, a reaction in which pigment builds up in skin or other tissues. The case was published in The New England Journal of Medicine by Aarti Maharaj and Michael Omar. In the report, the authors wrote that the condition “typically develops after months of treatment but may rarely occur with shorter courses.” The woman’s patches were described as asymptomatic, meaning they did not cause pain or itching. The visible changes, however, were striking, with dark areas ranging from bruise-like blue and purple tones to black.
Medical staff told the woman to stop taking minocycline and avoid sun exposure, because ultraviolet light can make some drug-related pigmentation worse. At a six-month follow-up, the discoloration had faded somewhat but was still visible. Doctors did not report that the reaction caused damage to internal organs. The report did not identify the woman’s hometown, the clinic where she was treated or whether she later received another rosacea medication.
Minocycline is sold under several brand names and is used to treat moderate to severe acne, inflammatory rosacea lesions and bacterial infections. The drug works by killing bacteria or slowing their growth, and it also has anti-inflammatory effects that can help some skin conditions. Its more common side effects can include dizziness, nausea, headache, fatigue and sensitivity to sunlight. Drug labels and medical references also list less common but more serious reactions, including severe skin and hypersensitivity reactions, tissue discoloration and pigmentation of the skin or mucous membranes.
The woman’s case was classified as Type II minocycline-induced hyperpigmentation. That form is linked to blue-gray discoloration on normal skin, especially on the arms and legs. Other forms have different patterns. Type I often appears as blue-black spots in scarred or inflamed skin. Type III can cause muddy-brown discoloration on sun-exposed skin. Some medical reviews also describe a Type IV pattern involving scars. Doctors believe the reaction may involve drug byproducts that bind to iron and melanin, then collect in immune cells in the skin.
The speed of the woman’s reaction stood out. Type II and Type III cases are often tied to longer use and higher total exposure to the drug. In this case, the visible changes began after a short course. Reports on how often the reaction occurs vary, and estimates depend on the patient group studied. Some studies of rosacea patients have found higher rates, while broader references describe it as uncommon. The exact risk remains unclear because patients take minocycline for different conditions, doses and lengths of time.
The case also shows how doctors weigh known benefits against rare harms when using older medicines. Rosacea can be difficult to control because it has several forms and can involve redness, swelling, bumps, pustules and visible blood vessels. Dermatologists may use topical medicines, oral antibiotics or light-based procedures depending on the symptoms. Minocycline remains one of the options for inflammatory lesions, but the case report said patients should be told about the risk of pigmentation before treatment begins.
There were no criminal, regulatory or court proceedings tied to the case. The next steps were medical rather than legal: stopping the suspected drug, watching the skin changes over time and considering treatment if the discoloration persisted. Some cases fade after the drug is stopped. Others can last for months or years, and reports have described laser therapy for patients seeking removal of stubborn patches. The woman’s six-month follow-up showed partial improvement, not full clearing.
The report did not say whether the woman had a prior history of drug reactions or whether she had taken minocycline before. It also did not say whether doctors performed a biopsy. The diagnosis was based on the timing of the symptoms, the pattern of discoloration and the known link between minocycline and tissue pigmentation. Doctors ruled the reaction notable enough to publish because the patches developed far earlier than the usual timeline for that subtype.
For now, the woman’s case stands as a rare example of a visible drug reaction that appeared soon after treatment began and remained months after the medicine was stopped. The next milestone is continued follow-up to see whether the blue-gray pigmentation fades further or requires additional therapy.
Author note: Last updated May 8, 2026.