Neuropathy refers to diseases or malfunctions of the nerves that commonly result in symptoms of pain, burning, tingling, and/or numbness. Neuropathy can have many causes including diabetes, spinal cord injuries, liver and renal failure, vitamin B12 deficiency, Guillain-Barre syndrome, hypothyroidism, some cancers, Lyme disease, HIV, several different pharmaceutical drugs, smoking, and a number of toxic exposures such as acrylamide, arsenic, lead, and thallium. Though there are several pharmaceutical drugs and other approaches that can be used in the treatment of neuropathy, natural medicines are under-recognized options. We discuss these natural medicines, as well as a handful of other miscellaneous therapies. We also discuss some underrecognized drug causes of neuropathy.
While there is general awareness that chemotherapy can cause neuropathy, there are several other potential neuropathy-inducing treatments for which there may not be the same level of awareness. Also generally not considered is that some of these drugs are frequently used in combination, which may be resulting in unknown risk of neuropathy for many patients.
Fluoroquinolone Antibiotics and Neuropathy
A case control study found that fluoroquinolone antibiotics are associated with an increased risk of peripheral neuropathy.Fluoroquinones are one of the most commonly prescribed classes of antibiotics today.
Insulin, Metformin, and Neuropathy
A retrospective study of over 84,000 patients with type 2 diabetes found that insulin monotherapy is associated with more than double the risk of neuropathy when compared to metformin monotherapy. Not only that, insulin was also found to be associated with more than double the all-cause mortality compared to metformin.Keep in mind that this increase in neuropathy risk is relative to metformin, and metformin in itself may already increase risk of neuropathy. Its use has been associated with vitamin B12 deficiency in diabetics, and vitamin B12 replacement has caused symptomatic improvement among patients with severe diabetic neuropathy.
Statins and Neuropathy
A 36-month study of 42 patients confirmed that long-term treatment with statins caused a clinically silent but still definite damage to peripheral nerves when the treatment lasts longer than 2 years.
Other Drugs and Neuropathy
A number of other drugs may also affect the development of neuropathy. These include but are not limited to certain blood pressure drugs, antibiotics, drugs for auto-immune diseases, anticonvulsants, and antivirals.
Unassessed Synergy of Risk Factors and Long-Term Risk
Though some argue the statin study shows that the issue of statins causing neuropathy is not clinically significant, we think this may be ignoring some other factors. We have to consider what happens after periods much longer than 2 years. Does the damage become relevant at some point? And what happens if other risk factors like insulin use and/or metformin use are simultaneously present? And what if such a person takes a course of fluoroquinolones in addition? This is one example of the limitations of evidence-based medicine. Typically, the adverse impacts of taking combinations of drugs have not in any way been studied prior to those combinations being used clinically. And here is an example where there is reason for concern. It is conceivable that there are many patients who are taking combinations of these drugs who are being set up for intractable neuropathy.