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Although various vitamins and supplements have been investigated in small studies or reported by doctors in case studies over the years, no strong scientific evidence yet exists for their effectiveness in PHN.
- Vitamin E
In an uncontrolled study, a group of 13 patients with moderate to
severe PHN ranging from several months to years responded to large
doses of vitamin E (d, alpha-tocopherol acetate, 400 IU two to four
times a day before meals (Ayres, 1973, 1975). Nine patients experienced
complete or almost complete relief, two were moderately improved and
two slightly improved. The role of Vitamin E cannot be determined
from this limited study.
- Adenosine monophosphate (AMP)
AMP, a compound that occurs naturally in the body, may have positive effects in the treatment of shingles and may play a role in limiting PHN. In one double blind clinical trial, 32 people who received injections of 100 mg of AMP three times a week for four weeks showed faster healing of herpes lesions and reduced pain. In addition, AMP appeared to prevent the development of postherpetic neuralgia. It is not known whether oral supplementation would have the same effect. AMP showed no side effects or toxicity during or after treatment (Sklar, 1981, 1985).
- Dietary soy
In a series of experimental studies on rats, it was found that soy diets suppressed the development of neuropathic pain behavior in rats (not tested specifically in PHN). Moderate intake was found to be effective in reducing levels of tactile allodynia and mechanical hyperalgesia, but not heat allodynia. High and low phytoestrogen levels were not found to be related to pain levels in these tests. This pain reducing effect, however, occurred only if the soy or phytoestrogen intake occurred before the nerve injury, not after. Further studies are necessary in order to determine if these findings can be applied to humans with neuropathic pain. (Shir, 2002)
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