If you have oral sex with an infected person, will you definitely get symptoms?

You will not only get symptoms, you will get anything they have.

You can take measures and precautions to see that it doesn't happen but remember anything you touch skin to skin no matter where it is could cause you to get infected with the same thing they have. Be safe and know you trust the person before you go that far.

Skin to skin does not transmit STDs unless the skin is "broken" for some reason. It's bodily fluids.

Yes, if you have contacted with an infected person you CAN get the symptoms and, as my colleague, "Tickle," said - the disease.

If you have oral sex with an infected person, will you definitely get symptoms?
Too vague; it depends on what they're infected with, what genders of the people involved are and who's doing what to who, and what type of oral sex we're talking about here.

HPV and Genital warts can be transmitted via oral sex. Doesn't matter who did what to do.

HIV is another case. Assuming you and the other person don't have ulcerations or open sores, you won't contract HIV orally. But, if you just bit your tongue or the inside of your cheek, that's enough to cause a problem.

Also, if it's the guy that has HIV and he ejaculates in the woman's mouth, the chances are higher for her to contract HIV than if it's the woman with HIV and the man performing oral sex on her. In order of disease concentration: blood, semen, vaginal fluid, breast milk.