Burning right after first intercourse is usually from small superficial tears at the vaginal entrance along with local irritation, and it settles over two to four days as those heal. Reduced natural lubrication makes it more likely, which is common when you are tense or anxious. The burning often feels worst when passing urine, because urine stings the raw surface. A true infection tends to develop later, over a day or two, with itching, discharge or a change in odour.
Next Steps
Use plain water for washing, keep the area dry, drink more water, and avoid intercourse until the discomfort has gone. If it has not improved in three to four days, book a gynaecologist examination.
Health Tips
Fever, heavy bleeding, a foul smelling discharge, or pain that is getting worse rather than better are reasons to be seen promptly.