Hot legs, characterized by a sensation of burning, tingling, or unusual warmth, are a common complaint with diverse underlying causes. This symptom is not a diagnosis, but a manifestation of a problem affecting the nervous system, the circulatory system, or the body’s metabolic balance. Understanding the source of this sensation is the first step toward finding relief, as it often results from nerve dysfunction, poor blood flow, or a systemic disease.
Neurological Sensations and Nerve Damage
The sensation of heat or burning often originates from a disruption in nerve function, known as peripheral neuropathy. This nerve damage causes faulty signaling that the brain interprets as pain or temperature changes. Small fiber neuropathy is the most common cause, affecting the nerve fibers responsible for transmitting pain, temperature, and itching sensations.
When these sensory fibers are damaged, they become hyper-excitable, leading to the spontaneous generation of pain signals and an unpleasant burning feeling. This abnormal sensation is a type of paresthesia or dysesthesia, occurring without an external stimulus. Symptoms typically follow a “stocking-glove” pattern, starting in the feet and progressing upward.
Restless Legs Syndrome (RLS) is another neurological condition that presents with similar discomfort. People with RLS describe the uncontrollable urge to move their legs as a burning, tingling, or “creepy-crawly” feeling, which tends to worsen at night or during periods of rest.
Circulatory and Vascular Issues
Problems with blood flow in the lower extremities can induce sensations of heat and burning. Chronic venous insufficiency (CVI) is a frequent vascular cause, where damaged valves fail to efficiently push blood back toward the heart. This malfunction causes blood to pool in the lower legs, leading to increased pressure (venous hypertension).
The pooling of blood causes fluid to leak into surrounding tissues, triggering inflammation and a sensation of warmth. This discomfort often feels heavy or achy and typically worsens after long periods of standing or sitting, improving with leg elevation.
In contrast, Peripheral Artery Disease (PAD) involves the narrowing of arteries, restricting the delivery of oxygenated blood. While PAD commonly causes pain that improves with rest, severe restriction can lead to nerve damage from lack of oxygen, manifesting as a burning sensation.
Systemic Conditions and Medication Side Effects
The underlying root of peripheral neuropathy is often a systemic disease or exposure to a neurotoxic substance. Uncontrolled diabetes mellitus is the most common cause globally, as high blood sugar levels damage the tiny blood vessels that nourish the nerves. This metabolic dysfunction interferes with nerve signaling and repair, resulting in the characteristic burning pain.
Other systemic conditions leading to nerve damage include chronic alcoholism, which has a toxic effect on nerve tissue. Nutritional deficits, particularly a severe deficiency in vitamin B12, are also linked to nerve damage causing burning and tingling sensations.
Certain medications can cause peripheral neuropathy. Classes of drugs known to cause this include some chemotherapy agents, antibiotics, and certain antiretrovirals. The damage can sometimes be reversed if the drug is discontinued early, but in severe cases, the nerve damage may become permanent.
Specific and Less Common Diagnoses
While most cases relate to common neuropathy or circulatory issues, a few specific diagnoses cause intense burning in the extremities. Erythromelalgia is a rare disorder defined by episodes of burning pain, redness, and increased skin temperature, most often affecting the feet. This condition is a vascular peripheral pain disorder where blood vessels episodically block and then become inflamed.
In some cases, Erythromelalgia is primary, caused by a gene mutation affecting sodium channels in the sensory nerves. Another localized cause is Tarsal Tunnel Syndrome (TTS), a compression neuropathy of the posterior tibial nerve inside the ankle. This entrapment causes tingling and burning, usually felt on the bottom of the foot. Compression can be caused by local factors like a cyst or bone spur, or systemic issues such as diabetes.