Itching that soon after sex is much more likely to be simple irritation than an STI. Most STIs don’t cause symptoms within a day or two. Friction during sex (especially if it was the first time with a new partner or if there wasn’t quite enough lubrication) can cause mild itching or soreness around the vaginal opening.
It could also be a mild reaction to something that was used during sex, like lube, condoms, or even soaps or wipes used before/after. Yeast or BV can sometimes flare up after sex too, but those usually come with discharge or a noticeable smell.
If the itching is only when you wipe and not constant, it’s probably just irritation and should settle down in a couple of days. Try to avoid scented products, wear breathable underwear, and keep the area clean but not over-washed.
If it gets worse, lasts more than a few days, or you notice new symptoms, it’s worth getting checked — but based on the timing, it doesn’t sound like an STI.
