viral cultures. differential diagnosis shingles can be confused with herpes simplex, dermatitis herpetiformis and impetigo, and skin reactions caused by contact dermatitis, candidiasis, certain drugs and insect bites. prevention main article: zoster vaccine shingles can be prevented by the chickenpox vaccine if the vaccine is administered before the individual gets chickenpox. if primary infection has already occurred, there are shingles vaccines that reduce the risk of developing shingles or developing severe shingles if the disease occurs. they include a live attenuated virus vaccine, zostavax, and an adjuvanted subunit vaccine, shingrix. a review by cochrane concluded that zostavax was useful for preventing shingles for at least three years. this equates to about 50% relative risk reduction. the vaccine reduced rates of persistent, severe pain after shingles by 66% in people who contracted shingles despite vaccination. vaccine efficacy was maintained through four years of follow up. it has been recommended that people with primary or acquired immunodeficiency should not receive the live vaccine. two doses of shingrix are recommended, which provide about 90% protection at 3.5 years. as of 2016, it had been studied only in people with an intact immune system. it appears to also be effective in the very old. in the uk, shingles vaccination is offered by the national health service (nhs) to all people in their 70s. as of 2021 zostavax is the usual vaccine, but shingrix vaccine is recommended if zostavax is unsuitable, for example for those with immune system issues. vaccination is not available to people over 80 as "it seems to be less effective in this age group". by august 2017, just under half of eligible 70–78 year olds had been vaccinated. about 3% of those eligible by age have conditions that suppress their immune system, and should not receive zostavax. there had been 1,104 adverse reaction reports by april 2018. in the us, it is recommended that healthy adults 50 years and older receive two doses of shingrix, two to six months apart. treatment the aims of treatment are to limit the severity and duration of pain, shorten the duration of a shingles episode, and reduce complications. symptomatic treatment is often needed for the complication of postherpetic neuralgia. however, a study on untreated shingles shows that, once the rash has cleared, postherpetic neuralgia is very rare in people under 50 and wears off in time; in older people, the pain wore off more slowly, but even in people over 70, 85% were free from pain a year after their shingles outbreak. analgesics people with mild to moderate pain can be treated with over-the-counter pain medications. topical lotions containing calamine can be used on the rash or blisters and may be soothing. occasionally, severe pain may require an opioid medication, such as morphine. once the lesions have crusted over, capsaicin cream (zostrix) can be used. topical lidocaine and nerve blocks may also reduce pain. administering gabapentin along with antivirals may offer relief of postherpetic neuralgia. antivirals antiviral drugs may reduce the severity and duration of shingles; however, they do not prevent postherpetic neuralgia. of these drugs, aciclovir has been the standard treatment, but the newer drugs valaciclovir and famciclovir demonstrate similar or superior efficacy and good safety and tolerability. the drugs are used both for prevention (for example in people with hiv/aids) and as therapy during the acute phase. complications in immunocompromised individuals with shingles may be reduced with intravenous aciclovir. in people who are at a high risk for repeated attacks of shingles, five daily oral doses of aciclovir are usually effective. steroids corticosteroids do not appear to decrease the risk of long-term pain. side effects however appear to be minimal. their use in ramsay hunt syndrome had not been properly studied as of 2008. zoster ophthalmicus zoster ophthalmicus. labels in serbian, from top: exudative erythema, scabs, blister, eyelid swelling treatment for zoster ophthalmicus is similar to standard treatment for shingles at other sites. a trial comparing acyclovir with its prodrug, valacyclovir, demonstrated similar efficacies in treating this form of the disease. the significant advantage of valacyclovir over acyclovir is its dosing of only three times daily (compared with acyclovir's five times daily dosing), which could make it more convenient for people and improve adherence with therapy. prognosis the rash and pain usually subside within three to five weeks, but about one in five people develops a painful condition called postherpetic neuralgia, which is often difficult to manage. in some people, shingles can reactivate presenting as zoster sine herpete: pain radiating along the path of a single spinal nerve (a dermatomal distribution), but without an accompanying rash. this condition may involve complications that affect several levels of the nervous system and cause many cranial neuropathies, polyneuritis, myelitis, or aseptic meningitis. other serious effects that may occur in some cases include partial facial paralysis (usually temporary), ear damage, or encephalitis. although initial infections with vzv during pregnancy, causing chickenpox, may lead to infection of the fetus and complications in the newborn, chronic infection or reactivation in shingles are not associated with fetal infection. there is a slightly increased risk of developing cancer after a shingles episode. however, the mechanism is unclear and mortality from cancer did not appear to increase as a direct result of the presence of the virus. instead, the increased risk may result from the immune suppression that allows the reactivation of the virus. although shingles typically resolves within 3–5 weeks, certain complications may arise: secondary bacterial infection. motor involvement, including weakness especially in "motor herpes zoster". eye involvement: trigeminal nerve involvement (as seen in herpes ophthalmicus) should be treated early and aggressively as it may lead to blindness. involvement of the tip of the nose in the zoster rash is a strong predictor of herpes ophthalmicus. postherpetic neuralgia, a condition of chronic pain following shingles. epidemiology