Hello, and i hope I can help you today. If your discomfort after sex is only on one side, it is likely that your labia might have gotten chafed by the rim of the condom or pulled inside you during intercourse, rather than an allergic reaction to the condom itself, as that would usually cause redness, itching and swelling of both your labia as well as vaginal itching and irritation. The best way to treat the inflammation is by avoiding sexual activity until the swelling goes down completely, and applying 1% hydrocortisone cream (which can be bought over-the-counter) to decrease inflammation. To help prevent chafing from condoms, you should use a water-based personal lubricant in addition to the lubricant on the condom, as it usually dries up quickly. You and your partner should rub your whole vulvar area and labia with lubricant right before initiating sex, and add more if it starts to feel dry. Switching to non-latex or non-spermicidal condoms (people can be allergic to one or both of these) can help prevent allergic reactions, however, your symptoms are not likely to be due to an allergy. I hope I was able to adequately answer your question today and that my advice was helpful. Best wishes, Dr. Brown