If the left side of the vulva is swollen and painful, if the redness is on the left side of the posterior vaginal union, it is often caused by a vestibular gland cyst combined with infection. If it is caused by a small local boil, this condition often appears as a local redness of about 1cm, and a white purulent spot may appear above the redness. It is recommended to take oral antibiotics for treatment and apply Bactrim locally, which will generally improve in about 5 days. It is recommended not to wear tight pants and not to eat spicy and sour stimulating food during the medication treatment.