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Causality: well established
Causality assessment · Causality: well established
Minocycline and Skin hyperpigmentation: is the FAERS signal real?
A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.
Minocycline ↔ Skin hyperpigmentation
n=188 co-reports · PRR 40.6 · ROR 41.2
Minocycline is the tetracycline best known for causing pigmentation of the skin, nails, sclera, and — rarely — internal organs, a distinctive effect not shared to the same degree by other tetracyclines. It is dose- and duration-related, appears after months of therapy, and typically fades slowly after withdrawal (though scleral and deep pigmentation can persist). The 188 co-reports (PRR 40.6) reflect the drug's long-term use in acne, where cumulative exposure is high, and the very visible nature of the change.
Regulatory basis: minocycline prescribing information (cutaneous and other hyperpigmentation warning). Established minocycline-pigmentation literature.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Pigmentation develops after months of exposure and slowly fades after withdrawal |
| Strength | met | PRR 40 on a modest co-report count |
| Consistency | met | Reproduced across decades of acne-treatment case series |
| Specificity | met | A distinctive minocycline effect, unlike other tetracyclines |
| Biological gradient | partial | Cumulative-dose-related; higher the longer the drug is taken |
| Plausibility | met | Likely melanin–drug complex deposition and iron deposition in the dermis |
| Coherence | met | Coheres with the labelled hyperpigmentation warnings and periodic skin review |
| Experiment | partial | Dechallenge (withdrawal) usually leads to slow improvement; no randomized trial |
| Analogy | met | Analogous to but more prominent than other drug-induced hyperpigmentation |
This page's own qualitative read, not an automated/citation-gated assessment.
✗ No ClinicalTrials.gov results-posting trial in the top search hits for minocycline captured skin hyperpigmentation; the effect takes months of cumulative dosing and is identified in dermatology practice rather than trial AE tables.