Shingles is a painful, blistering rash caused by the same virus that causes chickenpox. If you had chickenpox as a child, the virus never actually left your body. It stayed dormant in your nerve cells for years or decades, and shingles is what happens when it wakes back up. About one in three people in the United States will develop shingles at some point in their lifetime, and the risk climbs sharply after age 50.
Why the Virus Reactivates
The virus behind both chickenpox and shingles, called varicella-zoster, settles into clusters of nerve cells near the spine and skull after your initial chickenpox infection. It survives there in a dormant state, with its DNA tucked inside roughly 2 to 5 percent of sensory neurons. Special proteins keep the virus’s genes locked down and silent, sometimes for decades.
Reactivation happens when something disrupts that lockdown. The immune system’s ability to keep the virus suppressed naturally weakens with age, which is why shingles overwhelmingly affects older adults. Beyond aging, several factors can tip the balance: physical trauma or surgery near the spine, severe emotional stress, and anything that suppresses the immune system. Cancer treatments, organ transplants requiring immunosuppressive drugs, and conditions like HIV all raise the risk significantly. When the virus reactivates, it travels along the nerve fiber to the skin, which is why the rash follows the path of a single nerve.
How Shingles Feels and Looks
Shingles typically announces itself with pain before you ever see a rash. This early phase, known as the prodrome, lasts three to five days and produces burning, tingling, or a deep, dull ache in a specific strip of skin on one side of the body. The pain can be sharp enough to be mistaken for a pulled muscle, a heart problem, or a pinched nerve, depending on where it shows up. Some people also feel generally unwell, with low-grade fever and fatigue.
Then the rash appears. It starts as red patches that quickly develop into clusters of small, fluid-filled blisters. These blisters follow the path of a single nerve root, forming a band or strip that wraps around one side of the torso, or sometimes along the face, neck, or leg. The rash almost never crosses the body’s midline. New blisters continue forming for three to five days, then gradually dry out and crust over. The full rash typically heals within two to four weeks.
In rare cases, the virus reactivates in the nerve but never makes it to the skin, causing pain along the nerve path without any visible rash. This form is harder to diagnose and can be confused with other pain conditions.
Diagnosis
Most of the time, a doctor can diagnose shingles just by looking at the rash. The combination of a painful, blistering rash confined to one side of the body in a band-like pattern is distinctive enough for a visual diagnosis. Lab testing becomes useful when the rash looks unusual, when there’s no visible rash at all, or when the patient has a weakened immune system and the presentation is atypical. In those cases, a PCR test on fluid from a blister or a scab sample is the most reliable way to confirm the virus.
The Treatment Window
Antiviral medications can shorten the illness and reduce the severity of pain, but timing matters. Treatment is most effective when started within 72 hours of the rash appearing. The antivirals don’t kill the virus outright, but they slow its ability to replicate, which helps the rash heal faster, limits new blister formation, and lowers the chance of lingering complications. If you notice a painful, one-sided rash with blisters developing, getting to a doctor quickly makes a real difference in outcomes.
Pain management is the other pillar of treatment. Over-the-counter pain relievers help with mild cases, while more severe pain may require prescription options. Cool compresses and calamine lotion can ease the itching and discomfort of the blisters themselves.
Postherpetic Neuralgia
The most common complication of shingles is postherpetic neuralgia, or PHN: persistent nerve pain in the area where the rash was, lasting months or sometimes years after the skin has healed. Overall, about 5.8% of people with shingles develop PHN, but age changes that number dramatically. Among people 50 and older, the rate jumps to about 12.5%. Between ages 50 and 79, every additional decade of age increases the risk by roughly 70%. The pain can range from a constant burning sensation to sudden, stabbing jolts triggered by light touch, like clothing brushing against the skin.
PHN occurs because the virus damages nerve fibers during reactivation. Even after the infection clears, those damaged nerves continue sending exaggerated pain signals to the brain. For most people, PHN eventually fades, but in some it persists for years and significantly affects quality of life.
When Shingles Affects the Eye
Shingles can involve the nerve that supplies the forehead and eye, a form called herpes zoster ophthalmicus. This accounts for a significant share of shingles cases and carries serious risks. The first sign is often a rash on one side of the forehead, sometimes accompanied by headache and fever. If the rash extends to the tip of the nose, that signals the branch of the nerve connected to the eye is involved, making eye complications more likely.
About 50% of people with shingles in this area develop some degree of eye involvement, which can include inflammation of the cornea, the colored part of the eye, or deeper structures. Up to 25% of those with eye involvement go on to have chronic or recurring problems. Vision loss ranges from moderate (5 to 23% of cases) to severe (up to 8%), with complete vision loss occurring in less than 1% of cases. Some complications, like corneal damage from reduced nerve sensation, can develop months to years after the initial infection. If you notice a shingles rash anywhere near your eye or forehead, prompt evaluation by an eye specialist is critical to preventing long-term damage.
Can You Spread Shingles?
You cannot give someone else shingles. However, the fluid inside shingles blisters contains active virus, and a person who has never had chickenpox or the chickenpox vaccine can catch chickenpox from direct contact with that fluid or by breathing in virus particles from the blisters. The contagious window is specific: a person with shingles can spread the virus only while the blisters are open and oozing, not before the rash appears and not after the blisters have scabbed over. Keeping the rash covered with a bandage reduces the risk of spreading the virus to others.
Vaccine Protection
The shingles vaccine (Shingrix) is the most effective way to prevent the disease. It’s given as two doses, separated by two to six months. In adults aged 50 to 69 with healthy immune systems, the vaccine is 97% effective at preventing shingles. In adults 70 and older, effectiveness is 91%. Protection against postherpetic neuralgia specifically is 89 to 91%, depending on age. In people 70 and older, immunity remained strong for at least seven years after vaccination in clinical trials.
The vaccine is recommended for all adults 50 and older, regardless of whether they remember having chickenpox. (Most people born before 1980 carry the virus even if they don’t recall being sick.) Adults 19 and older with weakened immune systems are also recommended to get vaccinated, since they face higher risk of both shingles and its complications. In this group, effectiveness ranged from 68 to 91% depending on the specific condition affecting the immune system. You should still get vaccinated even if you’ve already had shingles, since the disease can recur.