If there are symptoms, they could include these 5:
Here are other symptoms that may indicate an STD.
But, the big BUT. STDs don’t always cause symptoms (i.e. you dont know you have one) or may only cause mild symptoms. So it is possible to have an infection and not know it. And even without symptoms, STDs can still be harmful and may be passed on during sex.
Yes, and that’s why they are such an issue, especially for young people – and why STD prevention should be a priority for them (and all of us).