ConditionInfections
Lyme Disease
Lyme disease is a bacterial infection caused by Borrelia burgdorferi (and related species), spread by the bite of infected blacklegged (deer) ticks. It is the most common tick-borne disease in the US and Europe. It usually starts with an expanding red rash called erythema migrans and flu-like symptoms. Untreated, it can spread to the joints, nerves and heart. A 10 to 14 day course of antibiotics, usually doxycycline, cures most people, especially when started early.
Also called: Lyme borreliosis, Borrelia burgdorferi infection, tick-borne Lyme
At a glance
- Cause
- Borrelia bacteria spread by blacklegged ticks, usually after the tick has been attached for 36 hours or more.
- Where
- Northeast, mid-Atlantic and upper Midwest US, parts of Canada, Europe and Asia.
- Early sign
- Expanding red rash (erythema migrans) 3 to 30 days after the bite, often with fever and aches.
- Later problems
- Facial palsy, meningitis, heart block, arthritis of large joints.
- Diagnosis
- The rash alone; blood tests for later stages.
- Treatment
- Antibiotics, usually doxycycline, for 10 to 28 days depending on stage.
When to get help
Call 911 or go to the ER
- Fainting, chest pain, shortness of breath or a very slow or irregular heartbeat after a tick bite or with Lyme symptoms (possible Lyme carditis): call 911 or your local emergency number
- Severe headache with stiff neck, confusion or high fever
See a doctor within a day or two
- An expanding red rash, with or without a central clear area, days to weeks after a tick bite or being outdoors in a Lyme area
- Fever, chills, headache and aches in summer after possible tick exposure
- Drooping of one or both sides of the face
- Shooting pains, numbness or weakness in the limbs
Book a routine appointment
- A swollen knee or other large joint that comes and goes, after time in a Lyme area
- Symptoms persisting after Lyme treatment
- A tick attached for more than 36 hours in a high-risk area, to discuss a single preventive antibiotic dose within 72 hours
Usually safe to manage at home
- A small red bump at a tick bite that appears within a day or two and fades within a few days (a normal bite reaction)
How Lyme disease spreads
Infected blacklegged ticks (Ixodes scapularis in the eastern US, Ixodes pacificus on the West Coast, Ixodes ricinus in Europe) pass the bacteria while feeding. Most infections come from tiny nymph ticks, about the size of a poppy seed, in late spring and summer. The risk of transmission is low if a tick is removed within 24 hours and rises after 36 to 48 hours of attachment. Lyme disease does not spread from person to person.
Symptoms by stage
Early localized (3 to 30 days after the bite)
- Erythema migrans (EM) rash: occurs in about 70 to 80 percent of people. A red patch at or near the bite that expands over days to 5 cm (2 in) or more, sometimes up to 30 cm. It may have a central clearing ("bull's-eye"), but many are uniformly red. Usually warm, not very itchy or painful. On darker skin it may look bruise-like or be harder to see.
- fever, chills, fatigue, headache, muscle and joint aches, swollen glands
Early disseminated (days to months)
The bacteria spread through the blood:
- multiple EM rashes elsewhere on the body
- facial palsy: drooping of one or both sides of the face. See Bell's palsy.
- meningitis: headache, neck stiffness, light sensitivity
- radiculoneuritis: shooting pains, numbness or weakness
- Lyme carditis: dizziness, palpitations, fainting or breathlessness from heart block
- eye inflammation
Late disseminated (months to years)
- Lyme arthritis: episodes of swelling and pain in large joints, especially the knee, often with large effusions but surprisingly little pain
- nerve problems: numbness, tingling, shooting pains, rarely encephalopathy with memory and concentration problems
- acrodermatitis chronica atrophicans: a skin condition mainly in Europe
Bite vs Lyme rash
| Normal bite reaction | Erythema migrans | |
|---|---|---|
| Appears | Within hours to 2 days | 3 to 30 days after the bite |
| Size | Usually under 5 cm | Expands to 5 cm or more |
| Course | Fades within days | Grows over days |
Diagnosis
- Early Lyme with EM rash: diagnosed clinically; blood tests are not needed and are often negative this early.
- Later stages: two-step antibody blood testing (an ELISA or EIA followed by a confirmatory test). Antibodies take 2 to 4 weeks to develop.
- Joint fluid PCR for Lyme arthritis; spinal fluid tests for neurological Lyme; ECG for suspected carditis.
Testing people without symptoms, or immediately after a tick bite, is not recommended. Unvalidated tests marketed by some labs should be avoided.
Treatment
| Stage | Typical antibiotics |
|---|---|
| Early localized (EM rash) | Oral doxycycline for 10 days, or amoxicillin or cefuroxime for 14 days |
| Facial palsy, radiculoneuritis | Oral doxycycline for 14 to 21 days |
| Meningitis | Oral doxycycline or IV ceftriaxone for 14 to 21 days |
| Carditis | Oral or IV antibiotics for 14 to 21 days; hospital monitoring if severe |
| Lyme arthritis | Oral antibiotics for 28 days; repeat or IV course if needed |
Doxycycline is now considered safe for short courses in children of all ages. Most people recover fully, especially with early treatment.
Persistent symptoms after treatment
Some people have fatigue, pain or difficulty concentrating for months after treatment. This is called post-treatment Lyme disease syndrome. Studies show that longer or repeated antibiotic courses do not help and carry risks. Symptoms usually improve gradually over time with supportive care.
Other tick-borne infections
The same ticks can carry anaplasmosis, babesiosis and Powassan virus. High fever, low blood counts or anemia, or poor response to treatment can suggest a co-infection.
Prevention
- Use repellents containing DEET, picaridin, IR3535 or oil of lemon eucalyptus on skin, and permethrin on clothing.
- Wear long sleeves and trousers tucked into socks in wooded or grassy areas.
- Stay on cleared trails.
- Check for ticks daily after being outdoors, including the scalp, behind the ears, armpits, groin and behind the knees; check children and pets.
- Shower within 2 hours of coming indoors.
- Tumble-dry clothes on high heat for 10 minutes to kill ticks.
Removing a tick
Use fine-tipped tweezers to grasp the tick as close to the skin as possible and pull straight up with steady pressure. Clean the area. Do not use heat, nail polish or petroleum jelly. In high-risk areas, if a blacklegged tick was attached for 36 hours or more, a doctor may offer a single dose of doxycycline within 72 hours of removal.
Frequently asked questions
What are the first signs of Lyme disease?
The first sign is usually an expanding red rash at or near the tick bite, appearing 3 to 30 days later and growing to 5 cm or more. It may look like a bull's-eye. Fever, chills, fatigue, headache and muscle and joint aches often accompany it.
Does every Lyme rash look like a bull's-eye?
No. Many erythema migrans rashes are evenly red without central clearing. They may be oval or irregular, and on darker skin can look like a bruise. The key feature is a rash that expands over several days.
How long does a tick need to be attached to spread Lyme disease?
In most cases, a blacklegged tick must be attached for at least 36 to 48 hours to transmit Lyme bacteria. Removing ticks promptly after outdoor activities greatly reduces the risk, which is why daily tick checks are important.
Can Lyme disease be cured?
Yes. Most people are cured with a 10 to 28 day course of antibiotics, depending on the stage. Early treatment works best. Some people have lingering fatigue or aches afterward, which usually improve gradually without more antibiotics.
What happens if Lyme disease is not treated?
Untreated, the infection can spread to the nervous system, heart and joints, causing facial palsy, meningitis, heart rhythm problems and recurring arthritis, especially of the knees. These later stages can still be treated with antibiotics.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Lyme disease, signs and symptoms; Testing; Treatment
- Infectious Diseases Society of America/AAN/ACR: Clinical practice guidelines for the prevention, diagnosis and treatment of Lyme disease (2020)
- American Academy of Pediatrics: Red Book, Lyme disease
- NHS: Lyme disease
- MedlinePlus: Lyme disease