1. Sudden Intense Headache 

If you experience severe head pain unlike any you've had before, especially if it peaks in seconds to minutes in any part of the head, it could signal a ruptured aneurysm, a blood vessel in your brain that suddenly bursts, requiring immediate attention.

It could also be shingles which can cause pain in the forehead days before the skin reaction erupts. Shingles is a painful flare-up of the herpes zoster virus that lies dormant in anyone who's had chicken pox. Contrary to common belief, sudden severe headaches are unlikely to be a sign of a brain tumor. 

 

2. Chest Pain

Any intense discomfort, heaviness or pressure — like an elephant sitting on your chest — could spell heart attack. It may be combined with pain radiating down an arm, nausea and vomiting, sweating, and shortness of breath. Women can experience more subtle symptoms, like fatigue, a burning sensation or upper abdominal pain. If these symptoms occur only during exertion, it could also be angina, which happens when the heart muscle temporarily doesn't get enough blood.

 

3. Unexplained Weight Loss

Losing more than 5 percent of your body weight — without trying — over a period of six months could mean cancer: Weight loss is a symptom in up to 36 percent of cancers in older people. It could mean endocrine disorders e.g. hyperthyroidism, an overactive thyroid. The condition also triggers restlessness, sweating, increased appetite and difficulty concentrating.

If your weight loss is accompanied by extreme thirst or hunger, fatigue and frequent urination, it could be a sign of diabetes.

 

4. Unusual Bleeding

Ulcers and colon cancer can cause rectal bleeding or black or tarry stools. If you haven't had a colonoscopy recently, talk to your physician. Vaginal bleeding can be linked to gynecologic cancers. Bloody vomit can result from stomach or esophageal cancer, and people with lung cancer can cough up blood. 

Blood in the stool may be due to hemorrhoids, while blood in the urine may be the result of a bladder or kidney infection. Vaginal bleeding long after menopause may be due to the growth of benign polyps or fibroids. Vomiting blood can result from a tear in the blood vessels or an ulcer in the stomach or esophagus. And coughing up blood can happen with noncancerous conditions, like bronchitis, pneumonia or tuberculosis.

5. High or Persistent Fever

Fever is your body's way of fighting infection. But fever of 103 degrees and higher warrants a trip to the doctor. It may indicate a urinary tract infection, pneumonia, endocarditis (inflammation of the lining of the heart chambers and valves) or meningitis, which may require antibiotics to clear up. A persistent low-grade fever — for several weeks — with no obvious cause is characteristic of some infections, including a sinus infection, and some cancers, like lymphoma and leukemia.

 

6. Shortness of Breath

When organs aren't getting enough oxygen, breathlessness can result. Sudden shortness of breath can indicate a pulmonary embolism — when a blood clot forms in the body's deep veins (usually in the legs), travels to the lungs and gets lodged in the lung's blood vessels. If you find yourself gasping after climbing two or three stairs or getting tired sooner than you used to, doctors will want to rule out chronic obstructive pulmonary disease (COPD), especially if it's accompanied by a cough and fatigue and you have a history of smoking. Irregular heart rhythm, congestive heart failure and other types of heart disease are additional possibilities.  

 

7. Sudden Confusion

If you're experiencing sudden confusion, personality changes, aggression or an inability to concentrate, it's important to see a doctor right away. In the worst case, a brain tumor or bleeding in the brain could be behind the delirium. If you're also experiencing slurred speech, difficulty finding the right words, or numbness or weakness in the face, hand or leg, stroke is a strong possibility. Get to the doctor immediately. Any delay beyond two to three hours may result in irreversible brain loss

8. Swelling in the Legs

An accumulation of fluid (called edema) in the extremities can be caused by a number of conditions, but the one that most concerns doctors is heart failure, when the heart cannot pump as much blood as the body needs. When that happens, blood backs up in the veins, causing fluid to accumulate in the body's tissues. Heart failure is suspected when both legs are affected and the patient also has shortness of breath, fatigue and chest tightness.

 

9. Sudden or severe abdominal pain

Sudden abdominal pain could signal that an aortic aneurysm has ruptured. Alternatively, sudden pain can indicate a perforated viscus (a hole in the stomach, intestine or other hollow organ), often due to an ulcer. Intestinal ischemia, which happens when blood flow to the intestines slows or stops, starving tissues of oxygen, can be a culprit, too. Each of these conditions is life threatening, requiring emergency surgery.

Abdominal pain is frequently due to gallstones, which are hard, pebblelike deposits that get lodged in a gallbladder duct, resulting in sharp pain as well as nausea and vomiting. Although irritable bowel syndrome can trigger painful spasms in the colon, the pain tends to come and go over time and may also cause constipation, diarrhea or alternating bouts of both.