Lyme Disease Tests: How Testing Works and Whether At-Home Tests Are Accurate

How Lyme Disease Is Diagnosed

A Lyme disease diagnosis isn’t based on a lab test alone. According to the CDC, a healthcare provider considers:

• Your signs and symptoms
• How likely it is that you were exposed to infected blacklegged ticks
• Whether another illness could explain your symptoms
• Laboratory test results, when testing is appropriate

In some cases, no test is needed at all. People who have the typical expanding Lyme rash (erythema migrans) and live in or have traveled to an area where Lyme disease is common can be diagnosed based on the rash alone. Testing at that early stage is less reliable anyway, because the body may not have made enough antibodies yet.

The Standard Two-Step Blood Test

Lyme bacteria only pass through the bloodstream briefly and in small numbers, so trying to detect them directly in blood is usually not practical. Instead, standard testing looks for antibodies, the proteins your immune system makes in response to the infection.

The CDC recommends using antibody tests that have been cleared by the U.S. Food and Drug Administration (FDA) and that follow a two-step process:

1. Step 1: a screening test. Usually an enzyme immunoassay (EIA or ELISA). If this test is negative, no further testing is needed.
2. Step 2: a confirmation test. If the first test is positive or unclear (equivocal), the lab runs a second test on the same sample. This is either a Western blot (immunoblot) or a second, different immunoassay, depending on the method the lab uses.

The result is considered positive only when both steps are positive. Using two tests together improves accuracy and reduces false-positive results.

IgM and IgG antibodies

You may see two types of antibodies on a report:

• IgM antibodies appear first. They can detect infection earlier, but they’re more likely to give false-positive results.
• IgG antibodies develop later and last longer.

According to CDC-hosted laboratory guidance, IgM results should only be used as a sign of recent infection during the first 30 days of symptoms. If you’ve been sick for longer than 30 days, only the IgG result should be interpreted.

Why Timing Matters

Antibody tests depend on how long you’ve been infected. The CDC notes that it can take several weeks after infection for your immune system to make enough antibodies to be detected. Tests may be falsely negative during the first few weeks, but FDA-cleared tests have good sensitivity after 4 to 6 weeks.

A 2016 review published in CDC’s Emerging Infectious Diseases journal reported that two-step testing detected only about 30% to 40% of infections in early illness, compared with roughly 70% to 100% in later, disseminated Lyme disease. Specificity, meaning the ability to avoid false positives, was high at every stage.

That’s why testing on the day of a tick bite isn’t useful: your body hasn’t had time to respond. If early infection is suspected and the first test is negative, providers may repeat testing on a new sample collected 7 to 14 days later.

Understanding Your Results

One of the most important points: if you’ve had Lyme disease, you’ll most likely still have antibodies for a long time after treatment, and you may test positive for years. That doesn’t mean you still have the disease. You can also get Lyme disease again even if you have antibodies from a past infection.

False positives are more likely in people who had little chance of exposure to infected ticks. That’s why the CDC strongly discourages testing people who don’t have typical symptoms or haven’t been in an area where Lyme disease is common.

At-Home and Point-of-Care Lyme Tests

You may see Lyme test kits sold online that let you collect a sample at home and mail it to a lab. Here’s what CDC-hosted laboratory guidance (April 2024) says:

• Point-of-care test: an FDA-cleared rapid test is available for use in healthcare settings as a first-step test. A positive or equivocal result still needs an approved second-step test.
• Over-the-counter collection kits: these have not been FDA-cleared and are not recommended.

The CDC also cautions that some laboratories that don’t accept private insurance may be offering tests that aren’t cleared by the FDA. Before ordering any Lyme test, check whether it’s FDA-cleared and follows the two-step process.

This doesn’t mean all at-home testing is unhelpful. At-home tests for other health markers, such as certain vitamins and nutrients, work differently and may be useful in the right situation. You can explore those options on our At-Home Testing hub. For Lyme disease itself, though, the most reliable route is an FDA-cleared two-step test ordered through a healthcare provider.

Tests the CDC Doesn’t Recommend

In 2005, the CDC and FDA warned about commercial laboratories using Lyme tests whose accuracy and clinical usefulness had not been adequately established. Examples they named include:

• Urine antigen tests
• Immunofluorescent staining for “cell wall–deficient” forms of the bacteria
• Lymphocyte transformation tests
• PCR tests on inappropriate samples, such as blood and urine
• Western blots interpreted using criteria that haven’t been validated and published

The 2016 CDC journal review also described CD57 tests as inaccurate for Lyme disease. In 2014, the CDC raised serious concerns about a laboratory-developed culture test because of false-positive results from laboratory contamination.

A lab being CLIA-certified means it meets basic quality standards. According to the CDC, it doesn’t prove that a specific test is clinically valid. FDA clearance is what shows that the test itself has been reviewed.

The CDC encourages patients to ask whether their Lyme testing used validated methods and whether results were interpreted using appropriate guidelines.

Should You Test the Tick?

Some companies offer to test a tick you’ve removed. The CDC generally doesn’t recommend this, because:

• Labs that test ticks aren’t required to meet the same quality standards as clinical labs, and results shouldn’t be used for treatment decisions.
• A positive tick doesn’t necessarily mean you were infected.
• A negative tick can give false reassurance, since you may have been bitten by a different tick without noticing.

Instead, watch for symptoms and contact a healthcare provider if they appear. Our guide on what to do after a tick bite covers removal and the symptoms to watch for.

Testing After Treatment

Many people wonder whether they can re-test after antibiotics to see if the infection is gone. According to CDC-hosted guidance, antibody tests shouldn’t be used to monitor treatment or determine “cure,” because antibodies can remain long after the infection clears. Response to treatment is judged by how your symptoms improve.

If you’ve been treated and still have lingering symptoms such as fatigue, brain fog, or aches, a repeat Lyme antibody test usually won’t explain why. Talk with your provider about other possible causes and practical ways to manage how you feel day to day. Our symptom guides and beginner’s guide to supplements can help you prepare for that conversation.

Questions to Ask Your Provider

• Is testing useful for me right now, based on my symptoms and when they started?
• Is this test FDA-cleared, and does it follow the two-step process?
• Will both IgM and IgG be interpreted, or only IgG?
• If my result is negative, should I be re-tested later?
• If my result is positive, what does it mean for my treatment?
• Should I be checked for other tickborne infections or other conditions?

Frequently Asked Questions

Are at-home Lyme disease tests accurate?

CDC-hosted laboratory guidance states that over-the-counter Lyme sample collection kits have not been FDA-cleared and are not recommended. An FDA-cleared two-step blood test ordered through a healthcare provider is the recommended option.

How long after a tick bite should I wait to get tested?

Antibodies can take several weeks to develop, and the CDC says FDA-cleared tests have good sensitivity after 4 to 6 weeks. Your provider can decide whether and when testing makes sense, based on your symptoms.

What is a Lyme Western blot?

It’s a second-step test that checks for antibodies to specific Lyme bacteria proteins. It should only be interpreted after a positive or equivocal first-step test.

Can a Lyme test be positive years later?

Yes. Antibodies can remain for months to years after infection, even after successful treatment. A positive result doesn’t necessarily mean an active infection.

Can Lyme disease be diagnosed without a test?

Yes. A provider can diagnose Lyme disease based on the typical expanding rash in someone who lives in or has traveled to an area where Lyme disease is common.

The Takeaway

The recommended Lyme disease test is an FDA-cleared, two-step antibody blood test, interpreted alongside your symptoms and tick exposure.

Timing matters: tests are often negative in the first few weeks, and positive results can last for years after treatment. Over-the-counter Lyme collection kits, tick testing, and several specialty tests are not recommended by CDC guidance.

If you’re unsure whether testing makes sense for you, a healthcare provider can help you choose the right test at the right time.