- Lyme disease is treated with antibiotics to kill the bacteria.
- If an Erythema migrans rash occurs, treatment should be started immediately without waiting for a blood test.
- The earlier treatment is started the more likely the patient is to recover completely.
- There are still some uncertainties about the most effective drug, dose and length of treatment.
- In the UK the NICE Guideline is the standard for treatment.
- For most cases the recommendation is 3 weeks of doxycycline at 100mg twice a day.
- Recovery may be quick or may take some time, with a gradual improvement over the days and weeks following treatment.
- Everyone should take their whole course of treatment even if they feel recovered before it is finished.
- In some cases, particularly those diagnosed late, symptoms can persist, but the cause of this is not yet known.
Choice of antibiotic
Because the bacteria causing Lyme disease quickly penetrate body tissues, it is recognised that it is important to have a drug with good tissue penetration and good penetration of the spinal fluid.
The antibiotics recommended by the NICE Guideline are doxycycline, amoxicillin or ceftriaxone as these are the drugs that have been used in clinical trials. Because these trials have shown very variable outcomes (anything from about one third to all of the patients recovering), and because investigations have shown that the bacteria can sometimes survive conventional courses [eg Ref 1] many doctors and researchers are looking for better treatment.
The NICE Guideline Committee issued 4 Research Recommendations, one of which is “Antimicrobial management of Lyme disease“. NICE states
“The evidence on the effectiveness of antimicrobial treatment regimens used in different presentations of Lyme diseases is of poor quality, out-dated and often based on small studies. ” NICE 2018
There is a view that ketolides (such as azithromycin), which show very high effectiveness in the laboratory , may have a place in treatment. NICE recommends azithromycin as an alternative, except for those with heart abnormalities.
See NICE Guideline – Management for recommended doses of each drug. Because the bacteria can penetrate the spinal fluid (though this does not always happen) it is important that high enough antibiotic concentrations are reached in the spinal fluid. Research has shown that doxycycline at 200mg twice a day achieves the necessary levels in the spinal fluid much faster than with the 100 mg twice per day .
This is why the higher dose is recommended if the disease is affecting the central nervous system, in a situation where IV ceftriaxone is not thought appropriate.
Duration of treatment
The minimum length of treatment recommended by NICE is 21 days and patients should complete the entire course even if they feel they have recovered earlier.
In some cases recovery may happen very slowly in the months following treatment. If patients get worse after treatment has finished, they should consult their doctor in case re-treatment is necessary, as NICE Guideline suggests.
Unfortunately UK consultants see few Lyme disease cases and experience is spread thinly across the UK’s GPs. Although a House of Lords debate supported a call for development of a national network of interested NHS clinicians, the NHS has as yet no specialists in Lyme disease.
Treatment of children
Because young children are usually smaller, those aged 12 and under are prescribed antibiotic dose according to their body weight, rather than the standard adult dose. Children aged under 9 are not recommended to have doxycycline because of side effects, and so amoxicillin is used instead. However, because amoxicillin does not penetrate the spinal fluid so well, IV ceftriaxone is recommended by NICE when the disease is affecting the central nervous system (Lyme neuroborreliosis) or the heart (Lyme carditis).
Doctors and parents should be aware that in children, a neurological examination may be normal despite infection reaching the central nervous system.
Patients might experience a worsening of symptoms on starting treatment. This is termed a Jarisch-Herxheimer Reaction (JHR) after the two people who documented it.
NICE recommends that people contact their doctor, but keep taking their antibiotics.
“Symptoms include a worsening of fever, chills, muscle pains and headache. The reaction can start between 1 and 12 hours after antibiotics are started but can also occur later and can last for a few hours or 1 or 2 days. The reaction is self-limiting and usually resolves within 24 to 48 hours.” NICE 2018
Note that a European trial found that unlike syphilis, in which the JHR occurs in the first 24 hours of treatment, “We suggest that Jarisch–Herxheimer-like reactions may be prolonged and may occur late during treatment.” 
- Long term and repeated electron microscopy and PCR detection of Borrelia burgdorferi sensu lato after an antibiotic treatment. Honegr, K, D et al. 2004.Central European journal of public health 12 (1) (March): 6-11.
- Antimicrobial susceptibility of Borrelia burgdorferi sensu lato: What we know, what we don’t know, and what we need to know. Hunfeld & Brade 2006 Wien Klin Wochenschr 118/21–22: 659–668
- Penetration of Doxycycline into Cerebrospinal Fluid in Patients Treated for Suspected Lyme Neuroborreliosis. Dotevall & Hagberg 1989Antimicrobial Agents and Chemotherapy, July 1989, p. 1078-1080
- Clinical presentation of childhood neuroborreliosis; neurological examination may be normal. Broekhuijsen-van Henten et al. 2010. Archives of disease in childhood 2010; 95(11), 910–4
- Duration of antibiotic treatment in disseminated Lyme borreliosis. Oksi et al 2007 European Journal of Clinical Microbiology and Infectious Diseases 2007, 26 (8): 571-81
- Prevalence of Persistent Symptoms after Treatment for Lyme Borreliosis: A Prospective Observational Cohort Study. Ursinus, J et al. 2021 The Lancet Regional Health – Europe 6 (2021) 100142.