My boyfriend and I started trying out anal sex a few months ago and we both really love it. He always makes sure I’m ready to take him and that I orgasm really hard from it. But lately when he slips into my ass it feels as though someone has just thrown me into a tub of ice. I get covered in goose pimples and it’s really unpleasant. The freezing cold feeling is worse when I am kneeling on all fours and he fucks me from behind. Have you ever heard of this before? How can I stop it so I can get back to loving anal sex again?
–Shivering in the South
In all my years of answering questions about anal sex, I’ve never gotten this one. So, I did some research about the phenomenon you described, including talking to a doctor. She had three theories about the experience.
First, your core body temperature can increase during any kind of sexual activity, and that increase in temperature could cause mild chills, but would not necessarily give you the extreme cold feeling you describe. Second, have you experienced any sexual trauma or abuse? Sometimes, we can push traumatic things out of our consciousness, but they rear their heads as our body responds in bizarre, unexpected ways. You did not indicate anything about that in your letter, but it may be a possibility.
Third, and most likely if there is no history of trauma, is that your vagus nerve is the culprit. The vagus nerve begins in the brain stem and extends through organs in the neck, chest, and abdomen all the way to the upper part of the transverse colon. It affects many areas of the body, including the heart, lungs, stomach, ears, pharynx, larynx, trachea, and esophagus; it is involved in many body functions, like breathing, blood circulation, heart rate, gastrointestinal peristalsis, and the regulation of body temperature. Anal penetration stimulates the rectum, which in turn stimulates the colon, which, for some people, can stimulate the vagus nerve. Stimulation of the vagus nerve can cause a variety of effects in different people, and in your case, the vagus nerve is sending a message to your brain that something unusual is happening; yes, the vagus nerve can be that unspecific. The brain responds by telling your body it’s cold, and you get your ice bucket sensation.
The important thing to know is that you’re not in any danger, this is just how your particular body responds. If it’s worse in doggie-style position, I suspect that’s because he’s probably deeper inside you then, closer to the lower colon, and more likely to affect the vagus nerve. I recommend you experiment with different positions, to see if you can find one that feels better. You can also teach your body to react differently. For example, some people faint at the site of blood, but can learn to overcome it by deep breathing, rationalization, and learning how to cope with the fear it raises in them. You can also learn to override the reaction; think of it as “mind over vagus.”