Signs and symptoms of autonomic neuropathy depend on the nerves affected. They might include:

• Dizziness and fainting when standing, caused by a sudden drop in blood pressure (orthostatic hypertension).
• Urinary problems, such as difficulty starting urination, incontinence, difficulty sensing a full bladder and inability to completely empty the bladder, which can lead to urinary tract infections.
• Sexual difficulties, including problems achieving or maintaining an erection (erectile dysfunction) or ejaculation problems in men. In women, problems include vaginal dryness, low libido and difficulty reaching orgasm.
• Difficulty digesting food, such as feeling full after a few bites of food, loss of appetite, diarrhea, constipation, abdominal bloating, nausea, vomiting, difficulty swallowing and heartburn, all due to changes in digestive function.
• Inability to recognize low blood sugar (hypoglycemia), because the warning signals, such as getting shaky, aren't there.
• Sweating abnormalities, such as sweating too much or too little, which affect the ability to regulate body temperature.
• Sluggish pupil reaction, making it difficult to adjust from light to dark and seeing well when driving at night.
• Exercise intolerance, which can occur if your heart rate stays the same instead of adjusting to your activity level.

Many health conditions can cause autonomic neuropathy. It can also be a side effect of treatments for other diseases, such as cancer. Some common causes of autonomic neuropathy include:

• Abnormal protein buildup in organs (amyloidosis), which affects the organs and the nervous system.
• Autoimmune diseases, in which your immune system attacks and damages parts of your body, including your nerves. Examples include Sjogren's syndrome, systemic lupus erythematosus, rheumatoid arthritis and celiac disease. Guillain-Barre syndrome is an autoimmune disease that happens rapidly and can affect autonomic nerves.

An abnormal attack by the immune system that occurs as a result of some cancers (paraneoplastic syndrome) can also cause autonomic neuropathy.

• Diabetes, especially with poor glucose control, is the most common cause of autonomic neuropathy. It can gradually cause nerve damage throughout the body.
• Certain medications, including some drugs used in cancer chemotherapy.
• Certain infectious diseases. Some viruses and bacteria, such as botulism, Lyme disease and HIV, can cause autonomic neuropathy.
• Inherited disorders. Certain hereditary disorders can cause autonomic neuropathy.

Factors that might increase your risk of autonomic neuropathy include:

• Diabetes. Diabetes, especially when poorly controlled, increases your risk of autonomic neuropathy and other nerve damage. You're at greatest risk if you have difficulty controlling your blood sugar.
• Other diseases. Amyloidosis, porphyria, hypothyroidism and cancer (usually due to side effects from treatment) also can increase the risk of autonomic neuropathy.