In a trial of 38, 546 people 60 and up, sponsored by the VA and Merck, a single dose reduced the incidence of shingles over the next three years by half and slashed severe cases of postshingles pain (usually lasting three months or more) by two-thirds, according to the results in the New England Journal of Medicine (June 2, 2005).
Two versions are offered: the BarkLimiter, which features a long-lasting (up to 10 months) user-replaceable battery, and the BarkLimiter Deluxe, which features a rechargeable battery that lasts up to three months.