Lyme Disease vs Lupus: How to Tell Them Apart

Lyme disease vs lupus comes down to cause: Lyme is a bacterial infection spread by tick bites, while lupus is an autoimmune disease, yet both can cause joint pain, fatigue, and a rash. No single test settles the question, so doctors weigh your exposure history, rash, organ involvement, and antibody results together, and a positive ANA on its own does not mean lupus.

Key Takeaways

• Lyme disease comes from a tick-borne bacterium. Lupus is an autoimmune disease in which the immune system attacks the body’s own tissues.
• A positive ANA appears in about 1 in 7 people in the United States, so it is a screening clue and not a lupus diagnosis.
• The best-documented false positives run from lupus to Lyme screening tests. In one study, a Lyme ELISA read positive in people with lupus and a second test did not confirm it.
• The evidence that Lyme disease raises ANA is thin and mixed, and it rests mostly on case reports.

You have joint pain, bone-deep fatigue, maybe a rash, and a lab report with a positive ANA. One doctor says lupus. Another says Lyme. A third says the labs look fine. Lyme patient Erika Schlick told Healthline that “Every time my labs looked ‘normal,’ I was told it was stress, anxiety, or an unknown autoimmune condition”. If that is you, the confusion is real and it has a reason. Our guide to Lyme disease misdiagnosis explains the wider pattern.

Lyme disease vs lupus at a glance

Lyme disease is an infection and lupus is an autoimmune disease, and that single difference explains most of what separates them in the table below. The overlap is just as real: both can cause fatigue, joint pain and swelling, fever, a skin rash, and symptoms that come in waves. Our page on Lyme disease joint pain covers the joint side in depth.

The Lyme rows come from the CDC’s Lyme symptom page and its overview of the cause. The lupus rows come from NIAMS and the CDC lupus symptom page.

Lyme disease vs lupus: key differences in cause, rash, exposure, and organs

The clearest differences between Lyme disease and lupus are the cause, the type of rash, your exposure history, and which organs are involved.

Erythema migrans is the expanding red rash that can appear at the site of an infected tick bite.

• Cause. Lyme disease is an infection with a known organism, while lupus is an autoimmune disease. The Lupus Foundation of America says lupus is not contagious.
• Rash. The CDC says erythema migrans appears in about 70 to 80 percent of infected people, 3 to 30 days after the bite. Some rashes lack the classic bullseye look, as our guide to the Lyme disease bullseye rash shows. A malar rash stays on the face, and lupus symptoms include sensitivity to the sun.
• Exposure history. A tick bite or time outdoors in the Northeast, mid-Atlantic, or upper Midwest raises the odds of Lyme. Lupus has no single exposure like a tick bite. NIAMS lists viral infections, sunlight, certain medications, and smoking as possible triggers, and the CDC says a close family member with lupus may slightly raise your chances.
• Organs. NIAMS says lupus can affect the skin, joints, heart, lungs, kidneys, blood cells, and brain. Later Lyme can involve nerves and the heart.

Our overview of Lyme disease symptoms lists the full range if you want to compare your own.

How Lyme disease is tested, and where tests fall short

The CDC recommends FDA-cleared, two-step antibody tests for Lyme disease, and those tests miss many early infections.

Two-tier testing is a two-step blood test for Lyme antibodies. In the standard version an enzyme immunoassay (EIA) comes first and a Western blot confirms it. In the modified version, both steps are EIAs.

The CDC clinician page describes both versions. A review by CDC scientists in Emerging Infectious Diseases puts the sensitivity of two-tier testing at 30% to 40% in early infection and 70% to 100% in disseminated disease. The CDC adds that antibodies take several weeks to appear, and its patient page says FDA-cleared tests have good sensitivity after 4 to 6 weeks, per CDC testing guidance.

Three limits matter for the lupus question:

• Early tests can read negative. Antibodies lag behind infection, so someone with early Lyme may hear “your tests are normal.” Our page on the false negative Lyme test explains why.
• The rash can be diagnosed without a test. The 2020 IDSA, AAN, and ACR guideline recommends clinical diagnosis for a compatible rash with tick exposure in an endemic area.
• Other conditions can cross-react. The CDC lists relapsing fever, syphilis, rheumatoid arthritis, and Epstein-Barr virus infection as causes of false-positive cross-reactions. Lupus does not appear on that CDC list, though older studies discussed below point to it.

Our guide to interpreting Lyme test results walks through each result, including the Western blot step.

How lupus is tested, and where tests fall short

Lupus has no single diagnostic test, so a rheumatologist combines your symptoms, an exam, and lab results, starting with the ANA.

The CDC says “there is no one test for lupus” and that “a rheumatologist can diagnose lupus.” NIAMS adds that almost all people with lupus have a positive ANA. Totally healthy people can test positive too.

ANA (antinuclear antibody) is a blood test that looks for antibodies aimed at the nucleus of your own cells. It is a screening test, not a diagnosis.

How common is a positive ANA in people without lupus? A 1997 study of “healthy” people in 15 laboratories found ANA positive in 31.7% at a 1:40 dilution and 5.0% at 1:160. A national US survey of 4,754 people aged 12 and older found 13.8% had ANAs, which the authors estimated at more than 32 million Americans.

Anti-dsDNA is an antibody to double-stranded DNA that doctors order after a positive ANA, and it is more specific. The Hospital for Special Surgery says that at high titers it is almost exclusively specific to people with lupus. The Lupus Foundation of America notes about half of people with lupus have anti-dsDNA, so a negative result does not exclude lupus.

Can Lyme disease cause a positive ANA or lupus-like symptoms?

The evidence that Lyme disease causes a positive ANA or lupus-like illness is thin and mixed, and what exists comes mostly from case reports.

We searched Europe PMC and PubMed under several phrasings and found no large study that measured ANA in people with confirmed Lyme disease. Here is what the literature does show:

• A child with a lupus look-alike rash. A 2018 case report described a 5-year-old with a facial butterfly rash for 5 months. Lupus was suspected and blood tests were normal, but a skin biopsy tested positive for Borrelia. The rash cleared after 28 days of antibiotics. The authors wrote that borreliosis “may mimic lupus and present high titers of antinuclear antibodies,” but this child’s blood tests were normal.
• Lyme and lupus together. A 2021 report described a 35-year-old woman with both conditions, and the authors judged Lyme the most likely trigger for her lupus. That is one patient.
• A small association study. In 27 people with fibromyalgia, those who were ANA positive had higher T-cell reactivity to Borrelia than those who were ANA negative. These were not Lyme patients, and the study shows a link, not a cause.
• A 2024 review. It describes how Borrelia may interact with the immune system, then says these associations “lack a precise explanation” and need more investigation.
• A small prospective study. A 2004 study tested 78 people referred for Borrelia serology, 31 of them antibody-positive, and found no significant difference in ANA frequency between the Borrelia-positive and Borrelia-negative groups. The authors concluded there is no increase in ANA in the early phase of Borrelia infection.

So a positive ANA in someone with tick exposure is worth a closer look, and it is not proof of Lyme. The better-documented false positives run the other direction.

A 1995 study tested 35 people with lupus and found 40% were positive on a Lyme ELISA, while immunoblots were negative in every ELISA-positive case. A 1993 report described three more false-positive Lyme ELISAs in people with lupus or related connective tissue disease. Those were older assays, and we did not find a source showing how today’s two-tier tests behave in lupus.

Why Lyme disease and lupus get mistaken for each other

Lyme disease and lupus get mistaken for each other because their symptoms overlap, both depend on imperfect blood tests, and each test result can look convincing alone.

The CDC says lupus “can be hard to diagnose since its symptoms are often mistaken for symptoms of other diseases.” Lyme disease has the same problem, and misdiagnosis can happen both ways. Fibromyalgia is a third common label, which our page on Lyme disease and fibromyalgia covers.

• Lyme labeled as an autoimmune condition. Joint pain, fatigue, and a positive ANA can lead to an “autoimmune” label before anyone asks about ticks. A 2024 review states that cases of misdiagnosis between Lyme borreliosis and autoimmune diseases show why accurate diagnostics matter.
• Lupus labeled as Lyme. A positive screening ELISA in a person with lupus can look like confirmed Lyme if the second step is skipped. That review warns that even highly specific tests can show false positives at low pretest probability.

For the full list of look-alikes, see our guide to diseases that mimic Lyme disease.

What to do next if you cannot tell Lyme disease vs lupus

Your next step is to gather dated results and your exposure history, then have a rheumatologist and a clinician who knows tick-borne illness read them together.

1. Write a timeline. Note when each symptom started, which ones come and go, and any rash, including a photo if you have one.
2. List every tick exposure. Include bites, hikes, camping, and travel, with dates.
3. Collect your labs. Bring your ANA with its titer and pattern, any anti-dsDNA result, and every Lyme test with its date and which steps were run.
4. Ask what else could explain each positive. A positive ANA and a positive Lyme screen each have other possible causes.
5. Ask about both specialists. A rheumatologist can evaluate you for lupus, and a clinician who treats tick-borne illness can read your Lyme testing.
6. Do not stop prescribed medicine on your own. Talk with the prescriber first.

Dr. Diane Mueller, ND, LAc, DAOM, evaluates patients for Lyme disease and its co-infections. The CDC says a rheumatologist can diagnose lupus. A Lyme disease specialist can review your history and past results for the Lyme side of the question.

Book a consultation with My Lyme Doc and we will go through your timeline and labs together. We see patients by video visit in 11 states.