Pain is unpleasant, but a necessary evil: it serves as our body’s internal alarm system when there’s something wrong, and let’s us know when we’ve pushed our bodies beyond their limits.

In some cases, however, pain can be the sign that you’ve developed a deadly, emergent condition that requires immediate medical attention. Many of these pains aren’t immediately associated with the conditions that cause them, so it’s important to be aware and take them seriously when and if they arise.

Here are a list of pains that should raise a red flag.

Leg Pain

Legs can cramp and feel pain for lots of reasons - after a long run, when you’ve been sitting in an awkward position for long periods of time, or if you’ve injured your muscle. Sometimes, however, leg or calf pain can be a sign of a potentially deadly condition known as deep vein thrombosis, or DVT. DVT is a condition where a blood clot develops in the leg. The clot may dislodge and travel to the lungs or heart, where it can kill in a matter of minutes, according to NBC News.

People are most susceptible to DVTs when they’ve been sitting for extended periods of time, such as on long airplane, car, or train rides. DVTs are also common in patients who’ve recently undergone surgery, in pregnant women, and in people who have been on bed rest. The leg pain associated with DVTs is often accompanied by swelling or bruising in the leg or calf, or behind the knee.

If you suddenly develop a sharp leg or calf pain, especially if you have any of the risk factors outlined above, you should get to an emergency room to be examined. An ultrasound can confirm the presence of a clot, and doctors can administer blood thinners to treat it before it dislodges.


Upper Back Pain

Back pain can signal many things - poor posture, bad choices in footwear, the lingering reminder of spending a long day on your feet. However, unlike the dull, throbbing pack pain that is associated with those activities, a sharp, searing pain in the upper back can be the symptom of something far more sinister and deadly: an aortic dissection.

According to Mayo Clinic, “An aortic dissection is a serious condition in which the inner layer of the aorta, the large blood vessel branching off the heart, tears. Blood surges through the tear, causing the inner and middle layers of the aorta to separate (dissect). If the blood-filled channel ruptures through the outside aortic wall, aortic dissection is often fatal.” This condition is often accompanied by a crippling pain in the upper back, and most commonly affects those who have high blood pressure or disorders like Marfan’s syndrome. This condition can lead to stroke, paralysis, kidney failure, or death.

Severe Abdominal Pain

Abdominal pain can be linked to a number of causes, from irritable bowel syndrome and food poisoning to constipation and, more seriously, appendicitis. In women, however, a sudden, sharp abdominal pain can also be the sign of a ruptured ectopic pregnancy. This can be especially true is that abdominal pain is accompanied by symptoms such as shoulder pain, strong pressure in the rectum, and a feeling of lightheadedness or fainting.

Women who are over 35, those who have become pregnant while using an IUD, along with those who have scarring from infections, surgery, or a ruptured appendix, can all be at a greater risk of ectopic pregnancies. Although some who suffer ectopic pregnancies, the cause is unknown. If you are sexually active and of childbearing age, even if you have an IUD or have had a tubal ligation, you may still be at risk for having developed an ectopic pregnancy, and you should take this symptom seriously, because untreated, it can be fatal.


Pain in the Jaw, Shoulders, or Neck

When we think of jaw pain, we almost always suspect that there is a cause related to some kind of dental ailment. However, for women, the pains listed above may be signs of an impending heart attack, according to Dr. Oz. These symptoms are often accompanied by a persistent nausea - symptoms that are not often immediately linked to a heart attack. And while these symptoms may be easy to overlook, up to 95 percent of women who have suffered a heart attack have experienced one or more of those symptoms up to a month before the attack itself.

If you’re experiencing pain in the jaw, neck, or shoulders, and you feel pressure or tightness in the chest, shortness of breath, dizziness or fatigue, persistent headache, nausea or vomiting, you could be experiencing a heart attack. You should call 911 - never drive yourself to the hospital because you could hurt yourself or another driver - and don’t second guess your symptoms. Heart attacks can be fatal if medical attention isn’t sought in minutes. If you are able, Dr. Oz advises chewing on an aspirin while waiting for the ambulance to reduce your risk or amount of permanent damage to the heart muscle.

Severe Headache

Headaches are the most common kind of pain we experience, and a headache can signify a number of ailments. They can be triggered by something as innocent as wearing our hair in a ponytail that’s too tight, or can be caused by stress or dehydration. However, a sudden, severe headache, known as a “thunderclap headache,” can be the sign of something called a bleeding stroke, or ruptured aneurysm.

If you or someone you know develops a headache that has a sudden onset and becomes crippling within a matter of seconds or minutes, it may be a sign that you’ve developed a ruptured aneurysm. This condition is fatal 40 percent of the time, according to the Today Show. They advise that you should seek help immediately, especially if your headache is accompanied by pain behind the eye, neck pain, or numbness on one side of your face.