You can't know for sure you don't have an STD unless you are tested. You can have an STD and not have any symptoms.
But, if you have had unprotected intercourse and you have any of the symptoms listed, you should consult your healthcare provider:
- Unusual discharge from the vagina or penis
- Pain or burning while urinating
- Painful intercourse (for women)
- Blistery sores
- Warts on genitals
Some people can have an STD and not have any early symptoms. You should always use condoms every time you have intercourse to help reduce your chances of getting an STD.