Hello and welcome to HCM. Thank you for your query. In such cases, some basic information goes a long way. It was important for you to mention the age of the patient, marital status, whether sexually active or not? This information helps the doctor in narrowing down the possible causes to such a presentation. Do not worry. I can still help, but my answer will include more possible causes. You could discuss them with your friend and find the cause. You may always write back to me for a more detailed explanation. For now, the possible causes are: -Friction from undergarments/clothes -Sexual intercourse -Masturbation (one of the most common causes) -Exercise -Activities like cycling, horse riding, etc. -Soap (irritants) -Allergies -Infections It is difficult to advice thoroughly on what exactly needs to be done to bring this down. But conventional methods include using an ice pack for 10-15 minutes, at least 4-5 times a day on the region and the use of medication to bring down the swelling (eg. non-steroidal anti-inflammatory drugs). Of course, this will only help if the cause is friction due to clothes or something more general. You could ask your friend to wear comfortable clothes or even avoid wearing undergarments till the swelling comes down. If the swelling does not come down within 24-48 hours without doing anything to further irritate the region, then please visit a gynecologist at the earliest. Either way, it is best to be on the safer side and consult a doctor. I hope I have succeeded in providing the information you were looking for. Please feel free to write back to me for any further clarifications. I would gladly help you. Best wishes.