What could cause a swollen labia minora?

Lots of things: If the sex is too rough, too long, too dry etc, the labia minora can become inflamed. It is not normal, but it is not uncommon. Using extra lubricant such as astroglide or pjur can help. Allergy to condoms can also cause the problem. It the problem persists, it is time to have your doctor examine you.

Swollen Labia Minora: Swollen labia can be arise from congenital causes, vascular, lymphatic, tumor, infection, trauma from intercourse, cyst enlargement, varicocoele, hidradenitis, fasciitis, and many other causes. It is best to see your gynecologist for an exam.

Trauma/infection: Trauma, infection or allergy.