Conditions with Similar Symptoms:

Between 10% and 30% of all doctor's office visits are due to symptoms that resemble those of fibromyalgia, including fatigue, malaise, and widespread muscle pain. Because no laboratory test can confirm fibromyalgia, doctors will usually first test for similar conditions. A diagnosis of many of the disorders below may not always rule out fibromyalgia, because it can accompany other common conditions.

Several conditions may overlap or coexist with fibromyalgia, and have similar symptoms. It is not clear whether these conditions cause fibromyalgia, are risk factors for the disorder, have causes in common with fibromyalgia, or have no relationship at all with it.

Chronic Fatigue Syndrome. There is a significant overlap between fibromyalgia and chronic fatigue syndrome (CFS). As with fibromyalgia, the cause of CFS is unknown. A doctor can diagnose either disorder based only on symptoms reported by the patient. The two disorders share most of the same symptoms. They are also treated almost identically. The main differences are:

• Pain with tender points is the primary symptom in fibromyalgia. Some patients with CFS exhibit similar tender pressure points; however, their muscle pain is less prominent.
• Fatigue is the main symptom in CFS. It is severe, is not caused by excessive work or exercise, and is not relieved by rest or sleep.

Some doctors believe that fibromyalgia is simply an extreme type of chronic fatigue syndrome. Physical evidence, however, indicates that the two disorders are distinct, and each has its own treatments.

Myofascial Pain Syndrome. Myofascial pain syndrome can be confused with fibromyalgia and may also accompany it. Unlike fibromyalgia, myofascial pain tends to occur in trigger points, as opposed to tender points, and typically there is no widespread, generalized pain. Trigger-point pain occurs in tight muscles, and when the doctor presses on these points, the patient may experience a muscle twitch. Unlike tender points, trigger points are often small lumps, about the size of a pencil eraser.

Major Depression. The link between psychological disorders and fibromyalgia is very strong. Studies report that 50 - 70% of fibromyalgia patients have a lifetime history of depression. However, only 18 - 36% of fibromyalgia patients have major depression.

Some studies have found that people who have both psychological disorders and fibromyalgia are more likely to seek medical help, compared with patients who simply have symptoms of fibromyalgia. If this is the case, study results may be biased, finding a higher-than-actual association between depression and fibromyalgia.

Depressed feelings in people with fibromyalgia can be normal responses to the pain and fatigue caused by this syndrome. Such emotions, however, are temporary and related to the condition. They are not considered to be a depression disorder. Unlike ordinary periods of sadness, an episode of major depression can last many months.

Symptoms of major depression include the following:

• Depressed mood every day
• Feeling worthless or inappropriately guilty
• Inability to concentrate or make decisions
• Insomnia or excessive sleeping
• Low energy every day
• Restlessness or a sense of being slowed down
• Significant weight gain or loss (of 10% or more of an individual's typical body weight)
• Suicidal thoughts

If several of the above symptoms are present, and none of the physical symptoms (particularly the tender points) of fibromyalgia exist, the condition is most likely major depression.

Chronic Headache. Chronic primary headaches, such as migraines, are common in fibromyalgia patients. Some experts believe that migraine headaches and fibromyalgia may even share common defects in the systems that regulate certain chemical messengers in the brain, including serotonin and epinephrine (adrenaline). Low levels of magnesium have also been noted in patients with both fibromyalgia and migraines. Chronic migraine sufferers who do not benefit from usual therapies may also have fibromyalgia.

Symptoms of a migraine attack may include heightened sensitivity to light and sound, nausea, vision problems (auras), speech difficulty, and intense pain that is mainly on one side of the head.

Multiple Chemical Sensitivity. Multiple chemical sensitivity (MCS) is a term that describes conditions in which certain chemicals cause symptoms similar to CFS or fibromyalgia. As with CFS and fibromyalgia, some experts are uncertain whether MCS is a medical problem or psychologically based condition. Because everyone is exposed to many chemicals on a daily basis, it is very difficult to determine whether chemicals are responsible for specific symptoms.

Experts have come up with criteria to help recognize MCS:

• Symptoms can be produced by exposure to the chemical at levels lower than the person previously or usually tolerated.
• Symptoms can be triggered by multiple substances that are chemically unrelated.
• Symptoms involve multiple organ systems.
• The condition is chronic.
• The symptoms always happen with repeated exposure to a chemical. (These are often common chemicals found in popular products, such as perfumes, fabric softeners, and air fresheners.)
• The symptoms improve when the chemical is removed.

Restless Legs Syndrome. About 15% of people with fibromyalgia have restless legs syndrome. Restless legs syndrome is an unsettling and poorly understood movement disorder that is sometimes described as a sense of unease and weariness in the lower leg that is aggravated by rest and relieved by movement.

Disorders Affected by the Sympathetic (also called Autonomic) Nervous System. Other conditions that commonly accompany fibromyalgia include:

• Chest pain and heart palpitations
• Mitral valve prolapse
• Sudden drop in blood pressure

Conditions That Do Not Rule Out Fibromyalgia

Certain stress-related disorders commonly occur with fibromyalgia, and have overlapping symptoms. In fact, some experts believe these disorders so often interact that they may all be part of one general condition.

• Chemicals and environmental toxins -- exposure to various chemicals and environmental toxins such as solvents, pesticides, or heavy metals (cadmium, mercury, or lead) can cause fatigue, chronic pain, and other symptoms of fibromyalgia.
• Irritable bowel syndrome
• Osteoarthritis -- a common form of arthritis that can coexist with fibromyalgia. The two conditions may be confused, particularly in elderly people. However, osteoarthritis causes joint pain, not widespread or generalized pain.

Osteoarthritis is a chronic disease of the joint cartilage and bone. It is often thought to result from "wear and tear" on a joint, although there are other causes, such as congenital defects, trauma, and metabolic disorders. Joints appear larger, are stiff and painful, and usually feel worse the more they are used throughout the day.

• Temporomandibular joint disorders

Some tests may be positive for one or more of these diseases. However, fibromyalgia should not be ruled out if the results are uncertain, these conditions have already been treated successfully, or the patient meets the criteria for fibromyalgia.

Multiple sclerosis. This condition may have symptoms similar to those of fibromyalgia. Magnetic resonance imaging (MRI) scans often detect patches of tissue in the brain that confirm multiple sclerosis (MS). MRI findings combined with other tests and clinical findings usually make this diagnosis fairly certain. However, some patients may have symptoms that suggest MS, but tests cannot confirm the diagnosis. Some of these patients may have symptoms similar to those of fibromyalgia.

Autoimmune diseases. Rheumatoid arthritis, systemic lupus erythrematosis, and Sjogren syndrome are usually easy to diagnose, but they may develop slowly and be difficult to diagnose at first. Even if a doctor determines that a patient is most likely to have fibromyalgia, the doctor should keep track of any changes in symptoms over time in case the patient actually has one of these other illnesses.

Lyme Disease. Lyme disease is a bacterial disease transmitted by ticks. Health care providers can usually diagnose early Lyme disease correctly, but a delayed response or recurrence of this disorder may be mistaken for fibromyalgia. Some experts believe that 15 - 50% of patients referred to clinics for Lyme disease actually have fibromyalgia. Late Lyme disease can usually (but not always) be ruled out using blood tests that identify the organism that causes this disease. If fibromyalgia patients are incorrectly diagnosed and treated for Lyme disease with prolonged courses of antibiotics, the drugs may have serious side effects.

Drugs and Alcohol. Fatigue is a side effect of many prescription and over-the-counter medications, such as antihistamines. Constant fatigue is also a symptom of drug and alcohol dependency or abuse. Health care providers should consider medications as a possible cause of fatigue if an individual has recently started, stopped, or changed medications. Withdrawal from caffeine can produce depression, fatigue, and headache.

Polymyalgia Rheumatica. Polymyalgia rheumatica is a condition that causes pain and stiffness. It generally occurs in older women. Tender points are also present with this disorder, although they almost always occur in the hip and shoulder area. Morning stiffness is common, and patients may also experience fever, weight loss, and fatigue. A higher-than-normal erythrocyte sedimentation rate (ESR) can help diagnose polymyalgia rheumatica. Elevated ESR, however, also occurs with other conditions. Polymyalgia rheumatica usually responds dramatically to low doses of a steroid medication such as prednisone. Because polymyalgia rheumatica is sometimes associated with a rare condition called temporal arteritis, which may cause blindness if not treated, an accurate diagnosis is important.