Limitations of IgM antibody tests for Lyme disease

IgM antibody tests for Lyme disease alone, whether performed at home or by a hospital laboratory, have significant limitations due to frequent false positives, especially when used indiscriminately without clinical correlation. A self-test result for anti-Borrelia IgM antibodies by itself should be viewed with caution until it is followed up with a consultation with a doctor.

Studies show that isolated IgM positivity in serum often lacks clinical value and can lead to over diagnosis and inappropriate treatment, with one study reporting a 25.5% false positive rate for IgM immunoblot and even higher for some immunoassays (Joyner et al., 2022; Hillerdal & Henningsson, 2021; Liu et al., 2023).

However, IgM testing may aid earlier diagnosis if applied selectively in acute cases and confirmed by immunoblot alongside clinical assessment (Joyner et al.,2022). Newer multiplexed assays combining IgM and IgG detection with machine learning classifiers demonstrate improved sensitivity and specificity compared to traditional two-tier testing, achieving high accuracy even in early disease stages (Ahern et al., 2025; Ghosh et al., 2024).

Despite these advances, guidelines emphasise the importance of combining serological results with clinical presentation, as solitary IgM reactivity is common among controls and can reduce test specificity (Hoeve-Bakker et al., 2024; Liu et al., 2023).

Summary

Overall, while IgM testing in isolation is not highly reliable, it can be useful within carefully designed diagnostic algorithms that include confirmatory testing and clinical context (Dessau et al., 2025; Hillerdal & Henningsson, 2021; Hoeve-Bakker et al., 2024).

References

Dessau, R., Raffetin, A., Eikeland, R., Fingerle, V., Henningsson, A., Hunfeld, K., Jaulhac, B., Lienhard, R., Lindgren, P., Markowicz, M., Mavin, S., Ornstein, K., Wijnveld, M., & Strle, F. (2025). The choice of study designs of diagnostic accuracy using Borrelia specific IgG and IgM antibodies for the diagnosis of Lyme borreliosis.. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. (web link)

Joyner, G., Mavin, S., Milner, R., & Lim, C. (2022). Introduction of IgM testing for the diagnosis of acute Lyme borreliosis: a study of the benefits, limitations and costs. European Journal of Clinical Microbiology & Infectious Diseases, 41, 671 - 675. (web link)

Hillerdal, H., & Henningsson, A. (2021). Serodiagnosis of Lyme borreliosis—is IgM in serum more harmful than helpful?. European Journal of Clinical Microbiology & Infectious Diseases, 40, 1161 - 1168. (web link)

Ahern, H., Aucott, J., Stafford, P., & Embers, M. (2025). A-256 Multiplexed serologic test with advanced machine learning classifier for single-tier diagnosis of Lyme disease. Clinical Chemistry. (web link)

Hoeve-Bakker, B., Kerkhof, K., Heron, M., Thijsen, S., & Van Gorkom, T. (2024). Evaluation of different standard and modified two-tier testing strategies for the laboratory diagnosis of lyme borreliosis in a European setting. European Journal of Clinical Microbiology & Infectious Diseases, 43, 2397 - 2406. (web link) 

Ghosh, R., Joung, H., Goncharov, A., Palanisamy, B., Ngo, K., Pejcinovic, K., Krockenberger, N., Horn, E., Garner, O., Ghazal, E., O’Kula, A., Arnaboldi, P., Dattwyler, R., Ozcan, A., & Di Carlo, D. (2024). Rapid single-tier serodiagnosis of Lyme disease. Nature Communications, 15. (web link)

Liu, X., Tabibzada, N., Lindgren, H., & Sjöstedt, A. (2023). Utility of Borrelia-specific IgM and IgG antibody titer determinations during a 12-year period – results from a clinical laboratory in Northern Sweden. Frontiers in Cellular and Infection Microbiology, 13. (web link)

Updated 14th March 2026

Whether your anti-Borrelia IgM test result is positive or negative, always speak with your pharmacist or doctor if you are anxious about your health or concerned about your symptoms.