Chest pain, sudden loss of vision or speech, and severe stomach pain need immediate medical attention. But what about more subtle symptoms? It can be hard to know when to seek medical care. Here's a list of seven symptoms that call for attention.

Losing weight without trying may be a sign of a health problem. An unexplained drop in weight could be caused by many conditions. These include overactive thyroid (hyperthyroidism), diabetes, depression, liver disease, cancer or disorders that interfere with how your body absorbs nutrients (malabsorption disorders).

If you've lost more than 5% of your body weight during the past 6 to 12 months talk to your health care provider.

Fever seems to play a key role in fighting infection. Persistent fever can mean you have an infection, including COVID-19. If you have a fever and other symptoms, such as cough and fatigue, contact your health care provider right away for medical advice. Your health care provider will likely recommend that you get tested for COVID-19. If you have emergency COVID-19 symptoms, such as trouble breathing, seek care immediately. If you need to go to a hospital, call ahead. Then health care providers can take steps to ensure that others aren't exposed.

A fever can also be a symptom of many other infectious diseases, from a urinary tract infection to tuberculosis. Some drugs can cause a fever.

Call your health care provider if your temperature is 103 F (39.4 C) or higher. And call your provider if you've had a fever for more than three days.

Strenuous exercise, extreme temperatures, obesity and high altitude all can cause shortness of breath. Shortness of breath also could be a sign of another health problem. If you have unexplained shortness of breath, especially if it comes on suddenly and is severe, seek emergency medical care.

Causes for breathlessness might include chronic obstructive pulmonary disease, bronchitis, asthma, pneumonia or a blood clot in the lung (pulmonary embolism). Other causes include heart and lung problems. Difficulty breathing can also occur with a panic attack — a sudden episode of intense anxiety that triggers severe physical reactions when there is no real danger or clear cause.

What's considered typical for bowel movements varies widely. Consult your health care provider if you notice unusual or unexplained changes in your bowel movements, such as:

• Bloody, black or tarry-colored stools
• Persistent diarrhea or constipation
• Pain in the stomach that doesn't go away

Changes in bowel habits could be a sign of a bacterial infection — such as campylobacter or salmonella infection — or a viral or parasitic infection. Other possible causes include irritable bowel disease and colon cancer.

Seek medical attention if you have sudden:

• Poor thinking skills
• Difficulty focusing or paying attention
• Behavior changes

These changes could be caused by many problems, such as infection, dehydration, poor nutrition, mental health conditions or drugs.

If you usually feel full too soon or after eating less than usual, get checked by your health care provider. You might have this feeling, known as early satiety, along with nausea, vomiting, bloating or weight loss. If so, be sure to tell your health care provider about these symptoms as well.

Possible causes of early satiety include gastroesophageal reflux disease, commonly known as GERD, and peptic ulcers. In some cases, a more serious problem — such as stomach cancer — could be a factor.

Bright spots or flashes of light can sometimes be a sign of a migraine. In other cases, sudden flashes of light could be a sign of a serious condition in which a thin layer of tissue at the back of the eye pulls away from its position (retinal detachment). Immediate medical care can help prevent permanent vision loss.