Can I get STI from giving or receiving oral sex?

Yes. 

Oral sex is actually quite a risky practice when it comes to stis 

Infections like herpes, human papillomavirus, chlamydia, hepatitis A, gonorrhea and syphilis can all be passed through oral sex 

It is extremely important to use a barrier like condom or dental dam or to avoid performing oral sex altogether when you are unsure of your partner’s health. 

Even if your partner isn’t crazy about the idea of using barrier, unless you are both getting tested and in a long term, monogamous relationship you shouldn’t take chances with your health. Protect yourself. 

Keep in mind that the person performing oral sex is the one at more risk of getting infected and therefore should have the final say about using protection.