Temporary swelling after sex is usually caused by friction, lack of lubrication, or minor tissue trauma, which can block lymphatic drainage temporarily. It can also result from a mild allergic reaction to latex condoms, lubricants, or hygiene products. To treat this, rest from sexual activity and apply a cold compress wrapped in a cloth for 10-15 minutes. You can apply plain petroleum jelly (Vaseline) to soothe the skin. For mild inflammation, an over-the-counter 1% hydrocortisone cream can be used sparingly for 2-3 days. If the swelling does not improve, is painful, or is accompanied by sores or discharge, please see a doctor for an evaluation.