When and how doctors test for Lyme disease

A doctor tests for Lyme disease by drawing blood and sending it to a lab to look for antibodies — proteins your immune system makes when fighting the infection. The timing of the test matters: antibodies take one to two weeks to show up after a tick bite, so a test done too early may come back negative even if you have Lyme disease. If you remember a tick bite or a bull's-eye rash within the first week, your doctor may start treatment without waiting for test results.

Most doctors use a two-step testing process. The first step is called an ELISA test (enzyme-linked immunosorbent assay), which screens for Lyme antibodies. If that test is positive or uncertain, the second step — a Western blot — confirms the result. This two-step approach reduces false positives, since Lyme antibodies can sometimes appear in people who don't have Lyme disease.

You don't need a referral to see a doctor about possible Lyme disease, but you do need to see one to get tested. Urgent care clinics, primary care doctors, and infectious disease specialists can all order Lyme tests. If you live in an area where Lyme disease is common and you have symptoms, your doctor may test you even without a confirmed tick bite.

Key Takeaways

  • Lyme disease testing requires a blood draw sent to a lab, and antibodies take one to two weeks to appear after infection.
  • Most labs use a two-step process: an ELISA test first, followed by a Western blot if the first test is positive or unclear.
  • If you have a bull's-eye rash or remember a tick bite within the first week, your doctor may start treatment before test results come back.
  • Testing is most accurate three to four weeks after the tick bite, when antibody levels are higher and easier to detect.

The ELISA test: the first screening step

The ELISA test is the standard first step for Lyme disease screening. A lab technician mixes your blood with Lyme bacteria proteins and watches for a reaction. If your immune system made antibodies against Lyme, those antibodies will bind to the proteins and create a color change that the machine can measure. The result comes back as negative, positive, or indeterminate (meaning unclear).

ELISA tests are sensitive, meaning they catch most true cases of Lyme disease. However, they can also produce false positives — positive results in people who don't actually have Lyme disease. This is why a positive ELISA alone is not enough to diagnose Lyme disease. Your doctor will order a Western blot to confirm.

Results typically come back within three to five business days, though some labs are faster. If your doctor suspects you have early Lyme disease based on symptoms and a tick bite history, they may not wait for results before starting treatment.

The Western blot: the confirmation step

If your ELISA test is positive or indeterminate, the lab performs a Western blot on the same blood sample. This test separates Lyme antibodies by size and checks for specific ones that only appear in Lyme disease. The result is more specific than ELISA, meaning it is better at ruling out false positives.

A Western blot result is reported as negative, positive, or indeterminate. The CDC has specific rules for what counts as a positive Western blot: you need antibodies in certain bands (protein markers) to be present. A positive ELISA followed by a positive Western blot confirms Lyme disease. If the ELISA is positive but the Western blot is negative, you likely do not have Lyme disease.

Western blot results take longer than ELISA — usually five to seven business days — because the test is more complex. Some labs batch samples and test them together, which can add a few extra days.

Timing: why when you test matters

Antibodies against Lyme bacteria develop slowly. In the first week after infection, antibodies are usually too low to detect, so a test may come back negative even though you have Lyme disease. By week two, IgM antibodies (the first type your body makes) start to appear. By week three to four, IgG antibodies (which last longer) become detectable and are more reliable.

If you were bitten within the past week and have a bull's-eye rash or flu-like symptoms, your doctor may diagnose Lyme disease based on the rash and history alone, without waiting for a test. Starting treatment early — within the first few weeks — is more effective than waiting for test confirmation.

If you were bitten more than three weeks ago, a negative test is more reliable. By that point, antibodies should be present if you have Lyme disease. However, some people who were treated early may never develop detectable antibodies, so your doctor will consider your symptoms and history alongside the test result.

What happens after a positive test

A positive Lyme test means you have been infected with the Lyme bacteria at some point. Your doctor will review your symptoms and the timing of your infection to decide on treatment. Early Lyme disease (within the first few weeks) is treated with oral antibiotics, usually doxycycline for adults or amoxicillin for children and pregnant people. Treatment typically lasts two to three weeks.

If Lyme disease has spread to your joints, heart, or nervous system, treatment may be longer or require intravenous antibiotics. Your doctor will examine you and may order additional tests — such as an EKG for heart involvement or a spinal tap for nervous system involvement — to guide treatment decisions.

A positive test does not mean you will definitely have symptoms or complications. Some people clear the infection with antibiotics and have no lasting effects. Others develop post-treatment Lyme disease syndrome, where symptoms like fatigue and joint pain persist after treatment. This is still being studied, and there is no test to predict who will experience it.

What happens after a negative test

A negative Lyme test means the lab did not find Lyme antibodies in your blood. If you were tested within the first two weeks of a tick bite, your doctor may repeat the test in one to two weeks, since antibodies take time to develop. If you have symptoms and a clear history of a tick bite in an area where Lyme disease is common, your doctor may treat you anyway, even with a negative test.

If you were tested more than three weeks after a tick bite and the result is negative, Lyme disease is unlikely. Your doctor will consider other causes for your symptoms. Some people have symptoms similar to Lyme disease from other tick-borne illnesses, such as babesiosis or anaplasmosis, which require different tests.

A negative test does not rule out other conditions. If your symptoms continue, tell your doctor. They may order tests for other infections or conditions that cause similar symptoms.

Other tests your doctor might order

Depending on your symptoms, your doctor may order tests beyond the standard Lyme blood test. If you have joint pain or swelling, they may test fluid from the affected joint for Lyme bacteria. If you have nervous system symptoms like facial paralysis or meningitis, they may perform a spinal tap to test cerebrospinal fluid. If you have heart symptoms, an EKG or heart ultrasound may be ordered.

Some people request tests for co-infections — other illnesses spread by the same tick that carries Lyme disease, such as babesiosis, anaplasmosis, or Powassan virus. These tests are separate from Lyme testing and use different blood samples or methods. Your doctor will order these only if you have symptoms suggesting co-infection or if you live in an area where co-infections are common.

Home test kits for Lyme disease are available online, but they are not regulated by the FDA and their accuracy is not may provide. A test ordered by your doctor through a certified lab is more reliable.

Frequently Asked Questions

Can I get tested for Lyme disease without seeing a doctor?

No. You need a doctor's order to get a Lyme test at a certified lab. Some online companies offer home test kits, but these are not FDA-regulated and their results are not reliable for diagnosis. A doctor can order a test at any visit — urgent care, primary care, or a specialist appointment.

How much does a Lyme disease test cost?

Cost varies by lab, insurance, and location. With insurance, your copay or coinsurance typically ranges from $0 to $100. Without insurance, the full cost is usually $100 to $300 for both the ELISA and Western blot. Ask your doctor's office or the lab for a price estimate before testing.

What if I test positive but have no symptoms?

A positive test without symptoms is unusual and may mean you were infected in the past and your immune system cleared it, or the test is a false positive. Your doctor will review your history and may repeat the test. Treatment is not recommended for asymptomatic positive tests.

Can I test positive for Lyme disease years after infection?

Yes. Lyme antibodies can remain in your blood for years or even a lifetime after successful treatment. A positive test does not tell you when you were infected or whether you are currently infected. Your doctor will rely on your symptoms and history to determine if you need treatment.

What should I do if I find a tick on my skin?

Remove it with tweezers by grasping it close to the skin and pulling straight out. Do not twist or squeeze the tick. Wash the area with soap and water. If you can, save the tick in a sealed bag or container — some labs can test ticks for Lyme bacteria. Watch for a rash or symptoms over the next few weeks and contact your doctor if they appear.