How Is Shingles Diagnosed?

Shingles, also known as herpes zoster, is a painful skin rash caused by the varicella-zoster virus (VZV). This is the same virus that causes chickenpox. After you have chickenpox, this virus can remain dormant within your body and reactivate later in life, causing shingles.

Shingles can appear anywhere on the body, but often occurs only on one side of the body or face. Aside from a rash, shingles can cause blisters that scab within seven to 10 days. In most cases, it resolves within two to four weeks. However, before the rash presents itself, most people experience painful itching and tingling around the area for several days.

If you suspect you have shingles, you should visit your healthcare provider or a dermatologist (a medical doctor who specializes in skin conditions) for a diagnosis as early as possible. They can then prescribe antiviral medication to treat shingles. The earlier you receive treatment, the more likely you are to prevent the rash from spreading further on your body. This way, you can avoid any serious complications, including vision loss, neurological issues, or skin infections.

Shingles Diagnostic Criteria

If you have shingles symptoms or a concerning rash, talk with your healthcare provider as soon as possible. Your provider can usually make a diagnosis by examining your symptoms, such as doing a skin check. In some cases, they may recommend additional tests to confirm your condition. 

Physical Exam

Your healthcare provider will perform a physical exam as part of a shingles diagnosis.

Typically, a shingles rash occurs only on one side of the body or face. The most common place for shingles rashes is on a band around one side of the waistline. The rash can be itchy, painful, and tingly.

When shingles occur on the face, the eyes and vision may be affected, leading to vision loss. If you have a weakened immune system, you may even experience a whole-body rash.

Your healthcare provider will also look for one or more of the following shingles symptoms:

• Burning, shooting pain
• Tingling, itching, or numbness of the skin
• Fluid-filled blisters
• Headache
• Chills
• Fever
• Upset stomach

During the first few days of having shingles, you may experience a rash that causes clusters of fluid-filled blisters. New blisters continue to form over the next three to five days. By that time, the blisters start to dry and crust over. It usually takes two to four weeks for the skin to heal, though scarring and skin discoloration can occur.

Medical History

Your healthcare provider will ask about your medical history to help establish a diagnosis. If you have ever had chickenpox or received the chickenpox vaccine (also called varicella vaccine), that means that your body has been exposed to VZV before. The virus usually remains dormant in your nerve cells throughout your life. But the virus can reactivate later in life, causing shingles.

You can only develop shingles after you’ve first gotten chickenpox or the chickenpox vaccine. Once you’ve had a bout of shingles and recovered from it, it’s also possible to get shingles again later on.

Your provider will also ask if you have received a shingles vaccine. This includes the recombinant zoster vaccine, or Shingrix. The CDC recommends two doses of this vaccine for adults who are either aged 50 and older, or 19 and older and immunocompromised. You can get vaccinated as long as you don’t currently have shingles, a fever, or an allergy to the vaccine. 

Shingles Tests and Procedures

For some cases, a visual exam of your symptoms may not be enough to confirm a shingles diagnosis. Diagnosing shingles may also be more difficult in children, immunocompromised people, those with atypical symptoms, or those who have shingles but don’t develop a rash. In these cases, a healthcare provider may recommend a shingles test. 

There are two most common shingles diagnostic tests: 

Polymerase chain reaction (PCR) test: This relies on a DNA sample from a blister to detect whether the virus is in your body. A healthcare provider will press a cotton swab on a blister to collect a sample of blood and fluid for testing. Or, your provider may scrape a tissue sample from your skin.

Antibody test: This tests for VZV antibodies in your blood to confirm whether or not you have a history of VZV infection. A healthcare provider will use a needle to draw the blood sample from your arm and into a vial.

Either test will likely take less than five minutes. Your provider will then send the sample to a lab for testing. Of the two tests, a PCR test is more sensitive for detecting VZV. However, when you don’t have blisters or you present with uncommon symptoms, an antibody test may be the better option.

Screening for Related Conditions 

Healthcare providers can usually distinguish shingles from other skin conditions. However, shingles can be misdiagnosed as any of the following:

• Herpes, a viral infection that causes sores, such as cold sores
• Impetigo, a bacterial infection that causes facial sores (usually in infants and young children)
• Contact dermatitis, a type of eczema
• Folliculitis, an inflammation of your hair follicles
• Scabies, caused by a bacterial infection
• Insect bites
• An allergic reaction
• Candidiasis, a type of yeast infection

If it is unclear what is causing the rash, your healthcare provider may order a shingles test.

A Quick Review

Shingles is a painful skin rash on one side of the body or face caused by the same virus as chickenpox. The virus remains in the nerve cells after people recover from chickenpox. If the virus reactivates and you develop shingles, you may experience an itchy, painful rash and fluid-filled blisters on your skin.

Your healthcare provider or dermatologist can usually diagnose you based on a visual examination of your symptoms. Your provider may also order a PCR test or an antibody blood test to confirm a shingles diagnosis.

If you think you may have shingles, seek medical care right away for a diagnosis and treatment plan.