Fibromyalgia (FM) is a chronic disorder defined by widespread pain and tenderness, along with symptoms like fatigue and cognitive difficulties. This condition is primarily understood as a problem with central nervous system processing, where the brain and spinal cord amplify pain signals. While patients with FM frequently report a variety of skin complaints, the disorder itself does not directly cause a distinct, identifiable rash. Skin issues are common, however, due to secondary factors such as side effects from necessary medications and the high rate of co-occurring conditions that do cause dermatological manifestations.
Fibromyalgia and Direct Skin Causation
Research does not support a direct, causal link between the underlying pathology of fibromyalgia and common dermatological rashes, such as hives or eczema. FM is classified as a neurosensory disorder, not a primary inflammatory or autoimmune disease that directly targets skin tissue. The condition involves central sensitization, where the nervous system becomes hypersensitive, which is distinct from the immune-mediated processes that cause most rashes.
Some studies have noted potential immune system irregularities, such as an increased presence of mast cells beneath the skin. These mast cells release chemicals that can cause symptoms like flushing and itching, though they do not typically manifest as a true rash. No characteristic rash is currently included in the official diagnostic criteria for the condition.
Non-Rash Skin Sensitivities in Fibromyalgia
Many individuals with FM experience sensory phenomena without a visible rash. One common complaint is generalized pruritus, or persistent itching, which occurs without visible skin lesions and is often neuropathic in origin. Patients frequently report sensations related to nerve hypersensitivity, such as burning, tingling, or formication (a feeling of insects crawling beneath the skin).
Another element is hyperhidrosis, which is excessive sweating not related to temperature or exertion, potentially leading to skin irritation. Another common sensitivity is allodynia, where non-painful touch, such as the brush of clothing, causes significant discomfort. Some patients also exhibit dermatographia, where light scratching leaves raised, red welts on the skin.
Rashes Caused by Common Fibromyalgia Medications
A frequent source of skin issues in the FM population is the medication used to manage the disorder’s symptoms. Drug-induced rashes can range from mild, transient reactions to severe dermatological emergencies. Antidepressants, particularly SNRIs like duloxetine, and tricyclic antidepressants, can cause various skin reactions, including urticaria (hives) or photosensitivity.
Gabapentinoids, such as pregabalin and gabapentin, have also been linked to skin-related side effects. These can include generalized itching, hives, or, in rare cases, severe drug eruptions that require immediate medical attention. Even nonsteroidal anti-inflammatory drugs (NSAIDs) can trigger allergic skin reactions in sensitive individuals. Tracking the onset of a rash relative to starting or changing a medication is an important step in identifying the cause.
Rashes Linked to Common Co-occurring Conditions
The most common reason for a person with FM to develop a rash is the presence of a co-occurring condition, or comorbidity, which frequently affects the skin. Fibromyalgia often overlaps with other rheumatic and autoimmune diseases that have distinct dermatological features.
Common comorbidities that cause rashes include:
- Systemic Lupus Erythematosus (Lupus), which frequently coexists with FM and is known for causing the malar rash, a characteristic butterfly-shaped redness across the cheeks and nose.
- Sjögren’s Syndrome, which can lead to cutaneous vasculitis, manifesting as purpura (small purple or red spots resulting from blood vessel inflammation).
- Inflammatory skin disorders like Psoriasis and Eczema, which cause scaly or patchy inflammatory plaques and occur more frequently in people with FM.
- Mast Cell Activation Syndrome (MCAS), which involves the inappropriate release of inflammatory chemicals and can cause recurrent episodes of flushing, widespread itching, and hives.