Diagnosing Herpes Zoster
While a typical case of herpes zoster is easy to diagnose, herpes zoster without a rash can be more difficult to diagnose, since its symptoms can be similar to those of several other diseases. Diagnosing herpes zoster initially involves taking the patient's medical history and performing a physical exam to look for signs and symptoms of herpes zoster. If a patient does not have the herpes zoster rash, or if the diagnosis is questionable, the healthcare provider may do a blood test. It is important to see a healthcare provider no later than three days after the rash starts.
Before making a herpes zoster diagnosis, your healthcare provider will ask you a number of questions (this is known as taking a medical history). Your healthcare provider will also perform a physical exam to look for signs and symptoms of herpes zoster.
A typical case of herpes zoster is easy to diagnose. The doctor might suspect herpes zoster if:
- The rash is on only one side of the body
- The rash erupts along one of the many nerve paths, called dermatomes, that stem from the spine.
The doctor usually confirms a diagnosis of herpes zoster if a person also:
- Reports a sharp, burning pain
- Has had chickenpox or the chickenpox vaccine
- Has blisters that look like chickenpox
- Is elderly.
Some people have burning, painful, itchy sensations on one area of skin, but they don't get a rash (or the herpes zoster rash has yet to appear). If there is no rash, the symptoms can be difficult to diagnose because they can be mistaken for several other diseases.
In cases where there is no rash, or the diagnosis is questionable, diagnosing herpes zoster can involve a blood test. If there is a rash, but it does not resemble a typical herpes zoster outbreak, skin scrapings from the sores can also be used.