Dear Dr. Peg,

I heard that oral sex can cause air emboli in women. My pregnant friend told me. As a nursing student, I am interested in how this can occur, and as a woman I am concerned about my chances of having one if I receive oral sex. Please help!
-Concerned Nursing Student

Dear Nursing Student,
Your chances of having an air embolus from receiving oral sex are about as slim as a page of this paper turned on edge.
First, for those that don’t know, air emboli are big bubbles of air in the bloodstream. One bubble is called an air embolus; more than one are air emboli. While it is normal to have microscopic amounts of oxygen and other gases in the blood, a bubble of air big enough to fill a vessel is not normal and can indeed be very dangerous. It acts like a clot, blocking blood flow to crucial areas. In the worst-case scenario, for instance if it blocks blood to the brain or heart, it can kill. The question is can enough air get into a woman’s body during oral sex to cause one of these bubbles in her veins?

An air embolus from oral sex is extremely rare. Let me repeat that. Extremely rare. There are only a few cases in the medical literature. Most of these happened when the woman was pregnant or just after she had a baby. This is because pregnancy causes the veins in and around the vagina and uterus to get bigger than usual. Dilated blood vessels have weaker walls. If air was forced into the vagina and uterus, a bubble could break through these weakened blood vessels and cause an embolus. This is probably why your pregnant friend had heard of air emboli. Her doctor might have advised her against receiving oral sex during pregnancy.

If you are not pregnant, it takes a lot of air under a lot of pressure to create an air embolus. Your partner would have to make a tight seal and blow hard, something that most women would not find pleasurable anyway. Minor air trapping often happens during oral sex, or during vaginal penetration. This is not a problem. Nor is gentle blowing or breathing on the skin of the vulva. Just don’t let your partner try to blow you up like a balloon, and you should be safe.

Peggy Spencer is a board-certified family physician. She has been a UNM Student Health physician for 17 years. Drop your questions into her box in the lobby of Student Health and Counseling, or e-mail her directly at
All questions will be considered, and all questioners will remain anonymous. This column has general health information only and cannot replace a visit to a health provider.