If you have a red bun on your glans, it is advisable to go to the hospital for a relevant examination to clarify the possible causes. The possible causes are as follows: first, local allergies, such as contact allergies or oral medications after allergies, called drug rash. The actual fact is that you can find a lot of people who are not able to get a good deal on a lot of things. The second is the fact that the warts, through unclean sexual contact, and infected with human papillomavirus, will appear local raised red bag, the surface is not smooth, accompanied by bleeding or pain when touched. The actual fact is that you can find a lot of people who are not able to get a good deal on this. Third, glansitis, which can appear as a localized red bun with small local herpes, pain or swelling.