Is kissing harmful to your health? With just one kiss couples can share more than 500 different types of disease-causing germs and viruses, warns the Academy of General Dentistry (AGD), a professional association of more than 35,000 general dentists.

"Not knowing who you are kissing could be as dangerous to your health as having multiple sexual partners," says AGD spokesperson Connie White, DDS, FAGD.

Before you pucker up again, Dr. White dishes on the most common diseases and viruses that you and your sweetie can transmit to each other while smooching:

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Cold Sores

Cold sores are caused by the herpes virus. They appear as tiny, clear, fluid-filled blisters that form around the mouth and lips. The sores are highly contagious, especially if they are leaking fluid. However, even sores that have scabbed over can be contagious.

"A wound near the lips is most often herpes," says Dr. White. "A good rule of thumb is that if a person has any visible sores near his or her lips, avoid intimate contact!"

Colds

If you feel a cold or flu virus coming on, Dr. White suggests avoiding a make-out session. Common cold and flu viruses can be transmitted very easily through contact with the saliva or nasal secretions of a sick person. Yuck!

Mononucleosis

Mononucleosis, also known as the "kissing disease," is easily communicated to others through kissing, as well as sharing food, a cup, utensils or straws.

Dr. White says that college students are more prone to developing mononucleosis, due to a lowered resistance and living in close quarters with other students.

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"People can look as healthy as can be, but you have no idea what kind of diseases they are carrying," says Dr. White. "To protect yourself, know the person you are kissing."

If you're still in the mood—and you and your partner are healthy—stealing some smooches may benefit your oral health by increasing saliva production. Saliva helps to wash away food particles and cavity-causing bacteria. It also protects teeth from decay by neutralizing harmful acids.

Dr. White shares these tips to keep your breath minty-fresh:

To Get Fresh Breath:

• Avoid spicy foods, such as onions and garlic, and coffee. These foods and drinks can be detected on a person's breath for up to 72 hours after digestion.
• Brush and floss your teeth at least twice a day. Remember to brush the tongue, cheeks and the roof of the mouth.
• Chew sugar-free gum after meals to wash away food particles that get stuck between teeth and cause yucky odors.