context: People who have irritable bowel syndrome ( IBS) tend to have other conditions along with it. Doctors aren't sure why it happens, but most of the time, there are things you can do to ease your symptoms, whatever their cause. Here's what you need to know about these related illnesses and what you can do to feel better. Problems digesting milk. One in three people with IBS don't feel good after they eat dairy products, a condition called lactose intolerance. They may have diarrhea, bloating, and gas. It could be that those foods irritate the already sensitive intestines of people with IBS. If you don't feel good 30 minutes to 2 hours after you eat milk, cheese, or yogurt, talk to your doctor. She might order tests to see how your body handles lactose, the sugar in dairy foods. You might need to cut back on the milk products you eat, but you can also try taking lactase tablets or drops to help you digest them. Trouble with joints, muscles, and bones. Two out of every three people with IBS also have conditions that affect these body parts, called rheumatic diseases. Symptoms can vary, but you might get skin rashes, muscle pain, and headaches. Depending on the problem you're having, different types of treatments can help. Talk to your doctor or see a rheumatologist to find out what might help you the most. Fibromyalgia . Up to 60% of people with IBS have this disorder, which causes lasting pain, stiff muscles, and tender spots around the body. People who have it also feel very tired and have trouble sleeping. Doctors suspect that IBS and fibromyalgia have a common cause, but they don't know what it is yet. To help you feel better, your doctor may prescribe pain medication, antidepressants, or sleep aids. Light to moderate exercise, stretching, and massage can help, too. Too much gut bacteria. Bacteria do important jobs in our intestines, like helping to digest our food and keeping us healthy. But people with IBS are more likely to have too many of these germs, a condition called small intestinal bacterial overgrowth ( SIBO). It can cause diarrhea that doesn't get better, weight loss, and a lack of vitamins in the body. Your doctor can do some tests to see if SIBO is the cause of your symptoms. If it is, antibiotics can kill the extra bacteria in your gut. Chronic fatigue syndrome ( CFS). This condition is just what it sounds like: a feeling of exhaustion that doesn't get better with rest. People who have it are often too tired to do simple, everyday tasks. Some researchers think that inflammation in the brain and gut, or problems with the bacteria in the intestines, may drive both CFS and IBS, which could explain why they sometimes happen together. Treatment varies depending on your symptoms. You might need help getting better sleep, like with good bedtime habits or medications. If pain is a problem, medicines, relaxation, massage, and other techniques can help. You can also talk to your doctor about treatments for depression, anxiety, or memory troubles. Endometriosis . This painful problem happens when tissue that normally lines the uterus grows outside of it instead. Women who have it are more likely to have symptoms of IBS such as belly pain, constipation, and bloating. Inflammation may be at the root of both conditions, although scientists aren't sure if that's why they often happen together. There is no cure for endometriosis, but doctors can prescribe drugs to ease the pain and to help with fertility if you want to have children. Celiac disease . Research suggests that as many as 1 in 5 people with this condition, in which the body can't digest a protein in wheat called gluten, also have IBS. The intestinal inflammation they get when they eat foods like pasta, bread, and beer may make them more likely to get IBS. Symptoms typically go away once you stop eating foods that have gluten. Anxiety and depression. Some doctors think that the stress of handling IBS symptoms can be tough for your mental health. Or it may be that your emotions affect hormones and nerves that can impact the activity of your gut. It's not clear what the link is, but for many people, IBS goes hand-in-hand with depression and anxiety. What can you do about it? Your doctor might talk to you about taking antidepressants or anti-anxiety drugs. But you might also find relief from talking to a therapist about how you're feeling and learning to replace negative thoughts with positive ones.