A persistent feeling of numbness, tingling, or “pins and needles” (paresthesia) in the sole of the heel indicates an issue with the nerves responsible for relaying sensory information to the brain. While temporary numbness, like a foot “falling asleep,” is harmless, chronic numbness suggests a specific problem. Determining the cause requires understanding if the nerve issue is localized right at the foot, part of a larger systemic disease, or referred from a problem higher up the body. The precise location of the symptom—the bottom of the heel—often points toward specific anatomical structures that may be irritated or compressed.
Localized Nerve Compression in the Foot
The most direct cause of numbness limited to the heel is localized nerve compression in the ankle or foot. This mechanical irritation prevents the nerve from correctly transmitting signals, leading to sensory changes. The posterior tibial nerve is the primary structure involved, traveling through a narrow passageway on the inside of the ankle called the tarsal tunnel.
Tarsal Tunnel Syndrome (TTS) occurs when this nerve is compressed within the tunnel, often due to swelling, fallen arches, or irregular growths like bone spurs. The posterior tibial nerve divides into branches that supply sensation to the sole of the foot, including the heel. When the nerve is pinched, numbness, tingling, or burning is felt in the foot and heel area.
A more specific form of entrapment involves the inferior calcaneal nerve, often called Baxter’s nerve. This nerve runs along the inner aspect of the heel bone and can become compressed between muscles or tissues. Baxter’s nerve entrapment is a common cause of chronic heel discomfort that can include numbness or tingling under the heel, and it is often misdiagnosed as plantar fasciitis.
Systemic Conditions Causing Nerve Damage
When heel numbness is not due to a local pinch, it may signal a generalized condition affecting the body’s entire nervous system. This widespread nerve damage is called peripheral neuropathy. It often begins in the longest nerves first, making the nerves extending to the feet particularly vulnerable to metabolic or chemical disruption.
Diabetes Mellitus is the most common systemic cause of peripheral neuropathy. Chronically high blood sugar levels damage the tiny blood vessels that supply the nerves, starving the nerve fibers of necessary nutrients. This damage typically progresses slowly and affects both feet simultaneously, often resulting in a “stocking” pattern of numbness starting in the toes and feet.
Other systemic conditions can also cause nerve damage. Nutritional deficiencies, particularly a lack of Vitamin B12, can impair nerve function. Chronic alcohol consumption can lead to alcoholic neuropathy, and conditions like hypothyroidism, chronic kidney disease, or autoimmune disorders can trigger peripheral neuropathy.
Referred Pain from Higher Nerve Roots
Numbness in the heel can also be a sensory manifestation of a problem originating in the lower spine. This is known as referred pain or lumbar radiculopathy, where a compressed nerve root in the back sends faulty signals down its path to the foot. The lower lumbar and sacral nerve roots, particularly the S1 nerve root, contribute to the formation of the sciatic nerve.
When a herniated disc or spinal stenosis compresses the S1 nerve root, symptoms can radiate down the leg and into the heel. This condition, commonly known as sciatica, often causes pain but can also present as numbness, tingling, or burning in the heel. The sensory change is caused by the disruption of the nerve signal where it exits the spine, not a problem in the heel itself.
When Numbness Requires Medical Evaluation
While minor, temporary numbness often resolves on its own, persistent or worsening heel numbness warrants a professional medical evaluation. A doctor can accurately differentiate between a localized entrapment, a systemic disease, or a spinal issue, which is necessary for effective treatment. Seeking an assessment is advisable if the numbness lasts more than a few weeks, despite attempts at rest or changing footwear, or if the sensation seems to be spreading.
Certain accompanying signs require prompt medical attention. These “red flag” symptoms include sudden onset of severe numbness, especially if accompanied by muscle weakness or difficulty walking. Numbness that affects both feet symmetrically without a clear cause might suggest a systemic neuropathy or a severe spinal issue. Loss of bladder or bowel control alongside heel numbness is a rare but serious indicator of significant spinal cord compression that requires emergency care.