The pain may come in waves: sharp enough that you catch your breath, then gone as quickly as it came. Or perhaps it's a dull, constant ache. Maybe you're spending what seems like hours in the bathroom — or just wish you could.

What Causes Belly Pain?

Pain is the body's way of signaling that something is going on. Stomach pain alerts us to something that's happening inside us that we might not know about otherwise.

Some reasons for stomach pain are obvious — like when someone gets hit in the gut or eats spoiled macaroni salad. Often, though, belly pain might be hard to figure out. With so many organs in the abdomen, different problems can have similar symptoms.

Here are some of the things that cause tummy troubles:

Infection

When bacteria or viruses get into a person's digestive system, the body reacts by trying to rid itself of the infection — often through vomiting or diarrhea.

• Bacterial infections cause what we call "food poisoning." Bacteria are also responsible for other conditions that may give a person belly pain, such as pneumonia, urinary tract infections, strep throat, sexually transmitted diseases (STDs), or the rare condition toxic shock syndrome.
• Viruses, another type of infection, are behind what we call "stomach flu." Both bacteria and viruses can be easily passed from person to person. The good news is you can often avoid them simply by washing your hands properly and frequently and not sharing cups, straws, or utensils with other people.

Constipation

Being constipated is one of the most common reasons for frequent belly pain. People usually become constipated because their diet doesn't include enough fluids and fiber.

Irritation and Inflammation

When one of the body's internal organs becomes irritated or swollen, that can bring on belly pain. Pain from problems like appendicitis, ulcers, irritable bowel syndrome, and inflammatory bowel disease (IBD) is the body's way of telling us to get medical help.

More Belly Pain Causes

Food Reactions

Food reactions can be more than eating too much or basic indigestion. When people are unable to digest certain foods, doctors say they have a food intolerance. Conditions like lactose intolerance often cause belly pain when a person eats the food (milk products in the case of lactose intolerance). If you notice a reaction after eating certain foods, make an appointment with your doctor.

Conditions like celiac disease (a reaction to proteins in certain grains) or food allergies (like peanut allergy) are different from food intolerance. They involve immune system reactions that can actually harm the body beyond just producing a temporary reaction. When someone has a true food allergy, they must always avoid that food — even a small amount could be deadly.

Reproductive Problems

The digestive system isn't the only cause of bellyaches. Menstrual cramps are a common example of pain in the reproductive organs. Infections in the reproductive system, such as pelvic inflammatory disease (PID) or other STDs, also can cause abdominal pain in girls.

Testicular injuries can make a guy feel sick or even throw up if they are particularly severe.

Women often feel nausea during pregnancy. Ectopic pregnancies (when the pregnancy implants in the wrong place) can cause abdominal pain. Because problems like ectopic pregnancy need to be treated immediately, girls who have belly pain and think they might be pregnant should call a doctor right away. And girls who have had unprotected sex should be tested for STDs — if untreated, they can cause problems like infertility and long-term pain.

Anatomical Problems

Some diseases or defects can interfere with the way the organs do their jobs, causing pain. Crohn's disease can cause the wall of the intestine to swell and scar enough that it may block the intestine.

Hernias can also block the intestines, as can growths like tumors. Torsion is a medical term that means "twisting." Torsion can affect the intestine, ovaries, and testicles, cutting off blood supply or blocking their functions.

Emotional Distress

When people get stressed out, anxious, or depressed, their emotions can trigger physical symptoms, such as headaches or stomach pain.

In addition to these causes, belly pain also may be a result of problems that can happen when people have certain illnesses, such as sickle cell disease or diabetes.

When to See a Doctor

Sometimes, what seems like one problem — food poisoning, for example — can turn out to be something more serious, like appendicitis. So contact a doctor if pain is very strong, you're vomiting a lot, you already have another health condition, or the discomfort gets worse over time, doesn't go away, or wakes you up while you're sleeping.

What Doctors Do

Your doctor will ask about your symptoms, about illnesses you've had in the past, or any health conditions that other family members have. Be honest with your doctor, even if a symptom seems embarrassing.

Your doctor will probably also give you a physical exam and might order tests, such as an X-ray, ultrasound, or blood test. It all depends on what the doctor thinks is causing the problem.

If stress or anxiety seem to be behind the pain, the doctor may recommend talking to a counselor or therapist to resolve the problem. As medical experts, they're trained to help people figure out what's behind their stress — and then provide advice on how to fix problems or handle them better.

What You Can Do

The good news is belly pain isn't usually serious in teens. Although people can get pain for many different reasons, most are easy to treat. You can even lessen your chances of getting belly pain by taking a few simple precautions:

• Wash your hands before eating.
• Don't overeat, and try not to eat right before going to sleep.
• Drink plenty of water and eat fiber-rich foods, such as fruits and vegetables, to keep food moving through your digestive system.
• Avoid foods that have passed their expiration date or have been out of the refrigerator longer than they should be.
• If you have a food allergy or intolerance, avoid eating foods that make you sick.
• Always use a condom when having sex to protect against STDs and pregnancy.

Reviewed by: Larissa Hirsch, MD
Date reviewed: September 2010