The sensation of blood feeling like it is burning is a common complaint that rarely points to an issue with the blood itself. This feeling, often described as internal heat or fire, almost always originates from the peripheral nervous system or a problem with circulation. Nerves are designed to transmit information about temperature and pain, but when they are damaged or irritated, they can misfire. This misfiring leads to the perception of heat, requiring us to look beyond the bloodstream to understand the cause.
Burning Sensation Originating in the Nerves
The most frequent origin of an internal burning sensation is damage or dysfunction in the peripheral nerves, known as peripheral neuropathy. These nerves carry sensory information from the limbs back to the brain. When their protective coating or internal structure is compromised, the damaged nerve fibers send distorted signals, generating the false sensation of intense burning, tingling, or prickling pain.
Nerve damage often begins in the longest nerves first, which is why the burning sensation commonly starts symmetrically in the toes and feet before spreading into the legs and hands. Poorly managed blood sugar from diabetes is the leading cause of this polyneuropathy, as high glucose levels chemically damage nerve structures. Metabolic imbalances beyond diabetes can also trigger nerve dysfunction, including severe deficiencies in B vitamins, particularly Vitamin B12, which is necessary for nerve health. Chronic heavy alcohol consumption is also toxic to nerve tissue, leading to neuropathy.
Burning pain can also arise from nerve compression syndromes, where physical pressure on a nerve root or trunk causes localized irritation and pain that radiates outwards. For instance, a herniated disc in the spine can press on a nerve root, causing a burning pain known as radiculopathy that shoots down the leg. A trapped nerve in the wrist, such as in carpal tunnel syndrome, can cause a burning sensation to spread into the hand and fingers. These mechanical compressions interfere with normal signal transmission, resulting in a misfiring the brain interprets as heat.
Restricted Blood Flow and Vessel Inflammation
When the burning sensation is related to physical activity, it often points to issues with the circulatory system rather than the nerves alone. Restricted blood flow, or ischemia, occurs when arteries narrow and cannot supply enough oxygen-rich blood to the muscles and tissues, especially during exertion. This lack of oxygen causes a buildup of metabolic waste products, which irritates the surrounding nerves and manifests as a burning or cramping feeling.
This mechanism is the hallmark of Peripheral Artery Disease (PAD), where plaque buildup narrows the arteries in the legs, causing pain known as claudication. This pain, a direct signal of tissue hypoxia (oxygen deprivation), typically worsens with walking and finds relief with rest. Another vascular cause is vasculitis, an inflammatory condition where the immune system attacks and inflames blood vessel walls. This inflammation constricts the vessels, reducing blood flow, which leads to nerve damage and subsequent burning pain.
Temporary burning can also result from a vascular spasm, as seen in Raynaud’s phenomenon. This condition causes the small arteries in the fingers and toes to temporarily narrow in response to cold or stress. As blood flow is restricted, the affected area turns pale and numb. When the spasm releases and blood rushes back into the vessels, the sudden return of circulation causes a painful burning sensation.
Systemic Triggers and Medication Side Effects
Beyond direct nerve damage or circulatory blockages, the burning sensation can be a secondary symptom of a systemic issue that alters the body’s internal chemistry. Endocrine and metabolic disorders, such as an underactive thyroid gland (hypothyroidism), are associated with generalized neuropathy. These conditions make nerves more susceptible to damage, leading to the gradual onset of burning or tingling. A rare systemic inflammatory condition is erythromelalgia, which causes episodes of severe burning pain, warmth, and redness, most commonly in the feet.
The body’s reaction to certain pharmaceutical agents can also trigger nerve-related burning pain. Medication-induced neuropathy is a known side effect of several drug classes whose compounds are toxic to the peripheral nerves. Chemotherapy drugs used to treat cancer are a common cause, as they damage nerve endings during treatment. Certain antibiotics, such as those in the fluoroquinolone class, and some medications for HIV or high blood pressure have also been implicated. These systemic exposures disrupt the cellular processes of the nerve, triggering pain signals.
Warning Signs and Necessary Medical Steps
When experiencing a burning sensation, it is important to observe accompanying symptoms to determine the urgency of medical evaluation. Certain “red flags” signal a need for immediate care, such as the sudden onset of burning alongside muscle weakness or an unexpected loss of feeling. A spreading redness or rash accompanied by a fever suggests a possible infection, such as cellulitis, which requires antibiotic treatment. Any new burning pain that occurs with changes in consciousness or a severe, sudden headache should also prompt an immediate emergency response.
For a persistent, non-emergency burning sensation, a medical professional will begin the diagnostic process by taking a history of the symptoms. Patients should track when the sensation occurs, its exact location, and what activities or times of day make it better or worse, as these details help narrow the cause. Diagnostic steps often include comprehensive blood tests to check for underlying systemic causes, such as diabetes, vitamin deficiencies, or signs of autoimmune inflammation. If nerve damage is suspected, specialized tests like a nerve conduction study or electromyography may be performed to assess the speed and strength of electrical signals. In cases of suspected nerve compression, imaging techniques like Magnetic Resonance Imaging (MRI) may be used to visualize the spinal cord and nerve roots.