Almost everyone has had a fever or back pain at some time in their life. Each of these symptoms has many causes when they appear separately. When fever and back pain occur together, this is often because of the coincidental occurrence of these two very common symptoms. But sometimes the combination can signal the presence of cancer or a serious infection. Understanding these conditions will help you know when to see a doctor.
Just a Coincidence
Usually when back pain and fever occur together, it’s just a coincidence that both of these common symptoms happen to occur at the same time. Back pain is often caused by tearing of the muscles or ligaments in the back, known as back strain, brought on by excessive or unusual exertion. The most common cause of fever is an infection, which is often an upper respiratory tract infection such as the common cold or strep throat. Back strain usually gets better with time and can be improved with rest, applying heat or cold and taking non-steroidal anti-inflammatory medications (NSAIDs) such as aspirin, ibuprofen (Motrin, Advil) or naproxen (Aleve). The common cold is due to a virus, which can be treated with rest, decongestants and NSAIDs, whereas strep throat is caused by bacteria and requires antibiotics.
Infections Causing Both Symptoms
In other infections, the back pain and fever are directly related. Some infections cause muscle pains in various parts of the body, including the back. The flu, caused by the influenza virus, is a common example of this type of infection. Less often, an infection in the abdomen or pelvis causes pain that is felt in the back. A kidney infection, for example, typically causes pain on one side of the back, as well as a fever. Nausea or vomiting, blood in the urine and painful urination may also occur with kidney infections.
Any bacterial infection that enters the bloodstream may set up an infection in or around the spine. This is more common in people with an impaired immune system, such as diabetes or HIV. Tuberculosis is an infection that can start in another body area -- usually the lungs -- and then travel through the bloodstream to the spine. Infections rarely begin in the spine, but they may occur after back surgery or another procedure involving the back, such as an epidural anesthetic in a pregnant woman.
Cancer as a Cause
Many cancers cause generalized symptoms, such as fever, night sweats, weight loss or fatigue. While cancers that originate in the spine are unusual, cancers that begin in other places often spread, or metastasize, to the spine. Cancers that frequently lead to spinal metastases include breast, lung, prostate, thyroid and kidney cancers, as well as lymphomas. While these cancers are usually detected before they spread to the spine, back pain from a metastasis is occasionally the first symptom. Radiation therapy is often used to treat spinal metastases.
When to Seek Medical Attention
See your doctor if you have a fever, significant back pain or both that last more than a few days. This is especially important if you have cancer -- either now or in the past -- or an impaired immune system. Seek immediate medical attention if you have any symptoms of damage to nerves arising in the back, such as numbness in the abdomen, genital region or legs, leg weakness or any abnormal bladder or bowel function. These symptoms, suggestive of cancer or infection in or around the spine, require prompt treatment to reduce the likelihood of permanent impairment.
Reviewed and revised by: Mary D. Daley, M.D.