Causes of numbness in the thumb include carpal tunnel syndrome, alcoholism, Lyme disease and multiple sclerosis, notes Mayo Clinic. Other possible causes of numbness in the thumb include amyloidosis, peripheral neuropathy, Reynaud's disease and ganglion cysts. Symptoms that accompany the numbness may include tingling or burning pain.
In carpal tunnel syndrome, the median nerve in the carpal bones becomes compressed, causing numbness in the thumb. This disease is common in people between the ages of 30 and 60. Other factors leading to the syndrome include obesity, infections, bone fractures, alcohol use, rheumatoid arthritis, a cyst or tumor in the wrist and extra fluids that accumulate during menopause or pregnancy. It may lead to several symptoms including clumsiness, numbness or tingling, pain in the wrist, poor coordination of fingers, weak grip and weakness in the hand, notes the United States National Institutes of Health's MedlinePlus.
Typically, numbness occurs due to damaged, compressed or irritated nerves in the arm and wrist. Infections that affect the peripheral nerves, such as diabetes, usually lead to numbness. A doctor requires detailed information about the symptoms to diagnose the condition. Patients may need to undergo several tests to confirm the cause before starting treatment. If certain drugs are causing the numbness, a doctor may prescribe alternative medications.