Updated July 22, 2025
For many illnesses, doctors rely on lab tests for diagnosis. Based on your symptoms, they have suspicion of what’s going on, and then run tests to confirm that suspicion. You may assume the same is true for Lyme disease. Current Lyme disease tests look for antibodies your body makes in response to the bacteria, not the bacteria itself. That means they can miss early infections, since your immune system may not have produced enough antibodies yet. Studies have shown that up to 50% of tests can result in false negatives during early disease.
What many people don’t realize is that a diagnosis of Lyme disease often relies heavily on clinical judgment, especially in the early stages. According to the CDC, a doctor should make a Lyme diagnosis based on your symptoms, medical history, tick exposure, and geographic area. Blood tests can help support that diagnosis, but they shouldn’t be used alone to determine if you do or don’t have Lyme. If your blood test comes back negative, that doesn’t necessarily mean you don’t have Lyme disease. If you suspect you may have Lyme and your test comes back negative, there are several questions you should ask your doctor:
If you have an Erythema Migrans (EM) rash, often shaped like a bullseye, that is a definitive sign of Lyme disease. Other common symptoms of Lyme include fever, fatigue, aches, chills, and swollen lymph nodes. The more a Lyme infection progresses, the further it spreads; it can affect every organ and system of the body, causing a wide variety of symptoms. For this reason, your doctor should take into consideration your complete medical history, not just your current symptoms. They also should take into account whether you have had a known or suspected tick bite, and whether you live in or have traveled to an area where Lyme is endemic (remembering that Lyme is not just in New England!).
The CDC recommends a two-step testing process. The first test is called an ELISA. If that test comes back negative, the CDC doesn’t recommend doing the second test. However, many ELISA tests can miss early infection. If your test comes back negative, ask if only the ELISA test was run, or if the second test (Western Blot or another ELISA) was done. If only the first ELISA was done, ask if you can do the second test.
The Western blot test measures your immune system’s reactivity against a panel of proteins found on the Lyme bacteria, which show up as bands on your test results. According to the CDC, you need to have five positive bands for the IgG Western blot for the test to be considered positive. A doctor may report a negative result even if you have some bands present, simply because it doesn’t meet the CDC criteria. It’s important to know that during early infection, your immune system may not yet have produced enough antibodies to trigger a positive Western blot, so a negative result doesn’t always rule out Lyme disease.
Because interpreting Lyme test results can be complex and no test is perfect, it’s important to keep an open dialogue with your healthcare provider. If your symptoms persist or worsen despite a negative test, especially if it has been several weeks since your possible tick exposure, you may want to consider retesting or seeking a second opinion.
Even if you test negative for Lyme disease, you could still have another tick-borne illness, like babesiosis or anaplasmosis. Ask your doctor to consider the symptoms of other tick-borne illnesses when making a clinical diagnosis, and to test for them.
A good Lyme Literate Medical Doctor (LLMD) will consider all of these questions when making a clinical diagnosis. Click here to find one in your area.
Since Lyme disease is the great imitator and symptoms are similar to so many other illnesses, your doctor should consider every possibility when making a diagnosis. But Lyme should not be quickly ruled out based on a test. Don’t take “no” for an answer until you’ve explored all of these questions.
The above material is provided for information purposes only. The material (a) is not nor should be considered, or used as a substitute for, medical advice, diagnosis, or treatment, nor (b) does it necessarily represent endorsement by or an official position of Global Lyme Alliance, Inc. or any of its directors, officers, advisors or volunteers. Advice on the testing, treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient’s medical history.