Choosing Wisely

Lyme Disease Tests

When you need them—and when you don’t

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Lyme disease is usually caused by a bite from a deer tick. The disease can cause joint pain, aching muscles, and a tired feeling. There are two blood tests for Lyme disease, but usually you do not need them. Here’s why:

You do not usually need tests to show that you have Lyme disease.

In most cases, there’s a clear sign of Lyme disease—a painless, spreading rash that often grows to look like a bull’s eye. If you have this rash, and you recently had a tick bite or were in an area known for Lyme disease, you don’t need a test. Instead, your doctor can just start treating you with antibiotics, as appropriate.

You do not usually need tests if you have vague aches and pains.

Some people get the blood tests for Lyme disease because they feel achy and tired. These symptoms are very common and often come from arthritis, depression, the flu, or other causes. If you only have these vague symptoms, Lyme disease is not usually the cause.

The blood tests can have false positives.

The blood tests can trigger false positives, suggest­ing that you have the disease when you really don’t. This can happen in up to one out of four tests.

This can lead to unnecessary treatment with antibiotics. These drugs are usually safe, but they sometimes cause side effects, such as nausea, vomiting, diarrhea, and increased sensitivity of the skin to sunlight. In rare cases, they can even cause dangerous allergic reactions.

Using too many antibiotics can also lead to the growth of drug-resistant bacteria. This means that bacteria in your body may get stronger and more difficult to treat in the future.

A false positive can also lead to more unneeded blood tests, urine tests, x-rays, and doctor visits.

If you have a false positive, you may not get treated for the real cause of your pain. For example, rheuma­toid arthritis is a disease that causes joint pain. It can lead to permanent and severe joint damage if you do not start taking the right medicines as early as possible.

The blood tests can be a waste of money.

The blood tests for Lyme disease cost about $230, according to, in addition to the cost of your doctor’s appointment. And if you have a false positive, you may also waste money on unneeded treatments.

So when do you need blood tests for Lyme disease?

In some cases, you can have Lyme disease without the rash. Or you may not see the rash before it goes away on its own.

In these cases, your doctor should ask you about your medical history and do a thorough physical exam. Your doctor should look for these signs that you might have Lyme disease:

  • You were in an area with ticks and Lyme disease.
  • You also have fever or redness, warmth, and swelling in one or a few joints at a time— usually the knees, shoulders, or wrists.

Other symptoms can occur later on. Talk to your doctor about testing and treatment choices.


Advice from Consumer Reports

This report is for you to use when talking with your health-care provider. It is not a substitute for medical advice and treatment. Use of this report is at your own risk.

© 2013 Consumer Reports. Developed in cooperation with the American College of Rheumatology. To learn more about the sources used in this report and terms and conditions of use, visit