Sex is supposed to be one of the most pleasurable experiences there is. Unfortunately, for millions of women, it's exactly the opposite: Painful. Irritating. Uncomfortable. In fact, as many as 75 percent of women will experience painful intercourse at some point during their lives. If sex is more likely to make you furrow your brow than curl your toes, keep reading to find out what could be causing your pain. It's the first step in finding your way to treatment. Pelvic inflammatory disease (PID). Sexually transmitted diseases (STDs) such as chlamydia and gonorrhea are often to blame for PID. It occurs when bacteria associated with these STDs cause an infection in your uterus, fallopian tubes, and other reproductive organs. As a result, you may experience pain in your lower belly, fever, painful urination, irregular periods, and pain during sex. Vulvodynia. As many as one in five women experiences this chronic condition, which affects the outside of the vagina, called the vulva. Women with vulvodynia may feel pain any time there's pressure against the vulva, such as when having sex—especially during penetration—but also when using a tampon, during a pelvic exam, or after sitting for a long period of time. Interstitial cystitis (IC). Women with IC experience recurring pain in the pelvis and bladder as well as an increase in urinary frequency and urgency. Another common symptom of the condition, which affects as many as 8 million U.S. women, is painful intercourse. With IC, your symptoms may flare up after sex. In one survey, about 90 percent of patients with IC said that their condition kept them from having sex altogether. Endometriosis. This condition occurs when the cells lining the uterus grow outside of the uterus. Over time, the cells may bleed or cause scars on the fallopian tubes, ovaries, and other parts of the pelvic area. Most women with endometriosis experience pain—painful periods, painful cramps, and painful sex. Vaginismus. With vaginismus, the muscles around the opening of your vagina clench and make it extremely difficult for your partner's penis to enter your vagina. When you try having sex, you may feel burning or stinging sensations. In some cases, women contract their muscles so tightly that intercourse becomes impossible. Getting help If you experience pain during sex, you may feel embarrassed discussing it with your partner or your physician. But you shouldn't be. Painful intercourse is common. And once you and your doctor determine its cause, it's also treatable, with medication, physical therapy, and in some instances surgery. Don't wait to talk with your doctor.