Shingles is a painful rash that’s caused by varicella zoster, the same virus that’s responsible for chickenpox. If you had chickenpox as a child, the virus hasn’t completely gone away. It hides dormant in your body and can reemerge many years later as shingles. There are about 1 million cases of shingles each year, according to the Centers for Disease Control and Prevention (CDC). About half of these cases occur among people over the age of 60.

Older adults are most likely to develop shingles, which is why the shingles vaccine is recommended for people age 60 and older. Zostavax is currently the only vaccine approved by the U.S. Food and Drug Administration (FDA) to prevent shingles. According to the CDC, the vaccine can reduce your risk of getting shingles by more than half, but the older you are the less effective the vaccine becomes. As a result, some people who get the vaccine may still get shingles. The ideal time for getting vaccinated is between 60 and 69 years old.

Getting vaccinated can also help you avoid painful nerve complications from the disease. Although the shingles vaccine is approved by the FDA for people ages 50 to 59, the CDC recommends waiting until age 60 to get the vaccine. This is because it’s not clear how long immunity from the vaccine lasts. It appears to be most effective the first five years after getting it. Even if you’ve had shingles before, you can still get the vaccine to decrease the likelihood of a future reoccurrence of it.

The shingles vaccine contains ingredients that can cause an allergic reaction in some people. Avoid the shot if you’ve ever had a reaction to gelatin, the antibiotic neomycin, or other ingredients in the vaccine. You also want to avoid the shingles vaccine if your immune system is weakened due to:

  • HIV, AIDS, or another condition that compromises your immune system
  • drugs that lower your immune response, such as steroids
  • cancer affecting the bone marrow or lymphatic system, such as leukemia or lymphoma
  • active tuberculosis
  • cancer treatment such as radiation or chemotherapy
  • organ transplant

Women who are pregnant or may become pregnant should also not get the vaccine. People with minor illnesses, like a cold, can be vaccinated but may want to recover before doing so.

Mild vaccine side effects

The shingles vaccine has been tested on thousands of people to ensure its efficacy and safety. Most of the time, the vaccine is safely administered without any side effects. When it does cause reactions, they’re usually mild. People have reported side effects including redness, swelling, itching, or soreness in the area of skin where they were injected. A small number of people have complained of a headache after being vaccinated.

Serious side effects

In very rare cases, people have developed a severe allergic reaction to the shingles vaccine. This reaction is called anaphylaxis. Signs of anaphylaxis include swelling of the face (including the mouth and eyes), hives, warmth or redness of the skin, trouble breathing, dizziness, irregular heartbeat, or a slow pulse. If you have any of these symptoms after getting the shingles vaccine, seek medical help right away. Anaphylaxis can be life-threatening.

Does the shingles vaccine contain thimerosal?

You may be concerned about additives to the shingles vaccine — especially thimerosal. Thimerosal is a preservative that contains mercury. It’s added then removed to some vaccines to prevent bacteria and other germs from growing in them. The worry about thimerosal arose when early research linked it to autism, although this connection has since been found to be untrue. The shingles vaccine does not contain any thimerosal.

The shingles vaccine is made from the live virus. However, the virus is weakened, so it shouldn’t make anyone with a healthy immune system sick. People whose immune system is weaker than normal do need to be careful. In very rare cases, people with a weakened immune system have gotten sick from the varicella zoster virus in the vaccine. Talk to your doctor if you suspect that you have a weakened immune system.

It’s perfectly safe for you to be around friends and family members — even children — after getting the shingles vaccine. Rarely, people develop a chickenpox-like rash on their skin after they’ve been vaccinated. If you get this rash, you’ll want to cover it. Make sure any babies, young children, or people who are immunocompromised and haven’t been vaccinated against chickenpox don’t touch the rash.