Lyme Disease

NICE Guideline [NG95] Lyme disease. Last updated Oct 2018.

Article Last Updated:22/10/2025

Background Information

Aetiology

Causative agent: Borrelia burgdorferi (spirochete)

Vector: various tick species

Risk factors (for tick exposure):

Grassy and wooded areas
South of England and Scottish Highlands

Clinical Features

Early localised Lyme disease – usually happens 7-14 days after tick bite:

Flu-like symptoms (non-specific)
Erythema migrans around tick bite
- Circular slowly expanding red ring with a central clearing
- Usually NOT itchy or painful or hot

Disseminated Lyme disease:

Neuropathy (neuroborreliosis)
- Cranial nerve palsy (bilateral facial nerve palsy is common)
- Radiculopathy
- Peripheral neuropathy
Arthritis
- Initial migratory arthralgia
- Late monoarthritis / asymmetric oligoarthritis
Carditis
- AV block
- Myocarditis, pericarditis

Guidelines

Investigation and Diagnosis

Diagnose and treat Lyme disease if:

Erythema migrans present (no further testing needed), or
Clinical suspicion + positive ELISA AND immunoblot test (see below for more details)

Erythema migrans is a circular, slowly-expanding red ring with central clearing that is usually NOT itchy, hot, or painful.

If the lesion is itchy / hot / painful, it is more likely to be a local reaction, instead of erythema migrans.

Diagnostic Approach

If erythema migrans is present → Lyme disease can be diagnosed without further testing.

If Lyme disease is suspected based on clinical features (without erythema migrans) → laboratory testing

1st line: ELISA (testing for antibodies against Borrelia burgdorferi)
- If +ve → immunoblot test
- If -ve → consider alternative Dx (if ongoing Sx and test done within 4 weeks of onset → repeat 4-6 weeks after)

2nd line: immunoblot test
- If+ve → diagnose Lyme disease
- If -ve → consider alternative Dx

ELISA is a screening test with high sensitivity, and immunoblot is a confirmatory test with high specificity, which can exclude false positives that ELISA might produce

Management

Approach

Offer treatment if Lyme disease is diagnosed (i.e. erythema migrans / +ve laboratory testing)
If <18 y/o → discuss with speicalist

Patients who are bitten by a tick and are asymptomatic (i.e. did not develop Lyme disease) do NOT require any treatment.

Choice of Treatment

Choice of antibiotics:

1st line: oral doxycycline for 21 days
2nd line: oral amoxicillin

Give IV ceftriaxone for 21 days if there is:

CNS involvement, or
Lyme carditis + haemodynamic instability

Be aware that doxycycline should NOT be used in children (BNF: only use in <12 y/o if there are no adequate alternatives); give amoxicillin instead as 1st line for Lyme disease.

Jarisch-Herxheimer Reaction

Jarisch-Herxheimer reaction is a treatment-related complication that can occur after treating Lyme disease (note it is most commonly associated with syphilis)

Mechanism: systemic inflammatory reaction secondary to rapid destruction of spirochetes (Borrelia burgdorferi is a spirochete)
Timing: between 1-12 hours after antibiotics are started

Clinical features:

Fever
Chills
Muscle pain
Headache
Exacerbation of existing rash

Management:

Self-limiting (usually resolves within 24-48 hours)
Advise the patient to keep taking their antibiotics
Supportive care

Jarisch-Herxheimer reaction is NOT an allergic reaction. However, it is important to be able to differentiate it from an allergic reaction (especially anaphylaxis).