Oral estrogen use raises odds of porphyria cutanea tarda, study says

Women taking estrogen-containing medications face up to 2.52 times the odds of developing porphyria cutanea tarda, a rare skin disorder marked by sun-exposed lesions and scarring, according to population-level research published in JAMA Dermatology.

Key Clinical Takeaways:

• Oral contraceptives raise the odds of porphyria cutanea tarda by 2.52, while combined hormone therapy increases odds by 2.18.
• The rare condition affects an estimated 5 to 10 individuals per 100,000, causing skin fragility and blistering.
• Transdermal estrogen formulations may pose less risk than oral estrogen because they enter the bloodstream through the skin, avoiding initial processing by the liver, though data on nonoral routes remain limited.

Danish Registry Analysis Uncovers Estrogen Risks

To do a wider and potentially more definitive study of the association than previously suggested in smaller studies, investigators analyzed Danish health registries covering the years 1995 to 2024. The study identified 438 women with newly diagnosed porphyria cutanea tarda at a median age of 61.16 years, comparing them against 43,800 matched control individuals.

Investigators classified estrogen exposure as having picked up a minimum of one prescription for medication containing estrogen during the 12-month period preceding diagnosis. Researchers adjusted odds ratios for risk factors and comorbidities, including HIV infection, liver disease, smoking-related conditions, and alcohol or drug misuse.

Contraceptives and Hormone Therapy Show Varied Odds

Different medication types and delivery methods showed distinct associations with the condition. Estrogen-containing contraceptives were associated with 2.52 times the odds of porphyria cutanea tarda (95% CI, 1.67-3.82). Estrogen-only hormone therapy showed 1.58 times the odds (95% CI, 1.23-2.03), whereas regimens combining estrogen and progestogen demonstrated 2.18 times the odds (95% CI, 1.53-3.11).

Route of administration also influenced the findings. Oral estrogen-only hormone therapy was associated with 2.44 times the odds of the disorder. By contrast, no statistically significant associations were found for vaginal estrogen and other nonoral formulations, including transdermal estrogen.

Clinical Perspectives on Safe Prescribing

Transdermal formulations may pose less risk than oral estrogen because they enter the bloodstream through the skin, avoiding the initial processing by the liver that occurs with oral medications. However, only seven patients with the disorder had used nonoral, nonvaginal estrogen formulations, limiting conclusions about the safety of these products.

Dr. Cory Simpson, an associate professor within the Department of Dermatology at University of Washington Medicine in Seattle who did not participate in the research, pointed out that oral estrogen users presenting with blistering hand lesions—particularly following sunlight exposure—along with dark urine should prompt clinicians to consider PCT as a diagnostic possibility.

Dr. Rebecca Karp Leaf, an assistant professor of medicine at Harvard Medical School and co-director of the Mass General Brigham Porphyria Center in Boston who was independent of the work, indicated that the results offer no justification to limit overall estrogen prescriptions given how infrequently the illness occurs. I wouldn’t avoid starting somebody on a combined oral contraceptive pill in her twenties because of a risk of PCT, Leaf said.

For women with a history of the condition who experience severe menopausal symptoms, transdermal estrogen may be worth considering once their disease is in remission, provided clinicians closely monitor for new lesions and changes in urinary porphyrin levels.

Disclaimer: The information provided in this article is for educational and scientific communication purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider regarding any medical condition, diagnosis, or treatment plan.