Here are the most common reasons you might feel pain during sex—and when to talk to your doctor.

1. You're not lubricated enough.
Having sex when you're not fully lubed up can be seriously uncomfortable. "The tissues are not engorged and lubricated and ready," says Dr. Coady. Luckily, there's a pretty easy fix. If you're not getting naturally aroused, spend more time on pre-intimacy. But even with pre-intimacy, some women need a little extra help (and that's totally OK). Look for a lube that's water-based (i.e., formulated without oil) if you're using condoms.

2. You used a new personal care product.
Another major culprit of transient pain is certain personal care products, says Dr. Coady. These include "creams and douches and contact irritants such as soaps," she says. These products are often full of chemicals that can be irritating to the super-sensitive skin on your vulva and inside your vagina. If you have any sort of issue, ask for a recommendation from your gyno, and if you have any sort of irritation or, worse, an allergic reaction after trying a new product, stop using it immediately and call your doctor.

3. You have an infection.
Yeast infections and urinary tract infections can make sex really uncomfortable. While these things are generally easy to treat on their own, Dr. Coady says they can be exacerbated (or first made evident) by sex. Your doctor will likely advise you to forgo sex while you're being treated for the infection. If the pain doesn't resolve, don't be afraid to head back to your doctor for a follow-up. "If there's pain in the bladder and it's consistent and antibiotics don't work, that should really be evaluated," Dr. Coady says.

4. You're constipated or bloated.
Both of these issues—especially bloat—can cause pelvic pain during sex. But, as Dr. Coady points out, they should be short-lived. If it's a consistent problem, let your doctor know.

5. You have a condition called vestibulodynia.
In some cases, the pain is more constant than situational, which could be a sign of a chronic issue like vestibulodynia—"an inflammatory disorder or process that occurs in the tissue at the vaginal opening," says Dr. Coady. Eighty percent of consistent sexual pain in women (premenopause) is caused by vestibulodynia, she adds. The condition causes pain when the sensitive area is provoked in any way, sexual or not—even by a tampon. If you're having pain at the opening of your vagina on a regular basis, get it checked out to know for sure whether this is the case, and to get treatment.

6. Your pelvic-floor muscles are shortened, overactive, or in spasm.
The muscles in your vagina might tense up due to vestibulodynia, but it can also be a sign of more serious conditions like interstitial cystitis or painful bladder syndrome. These conditions can cause the muscles to become shortened or overactive, Dr. Coady says, because they're reacting to another issue in your body. Your doctor may refer you to a pelvic floor physical therapist.

7. You have another undiagnosed problem.
Whether there's an ongoing issue or not, it's important to "know your anatomy," Dr. Coady says. "Know how you look and know your baseline of feeling fine," she says. If you feel something outside of that baseline, always get it checked out. "Never ignore pain," Dr. Coady says.
More important, don't let anyone tell you it's just in your head. "The most important thing is self-advocacy," Dr. Coady says. "If your doctor says they don't see anything and it must be in your head, the mistake would be to not change doctors. Anyone who says they can't help you, or that there's nothing there, is not the right doctor."