Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 2012;85(11):online

See related article on Lyme disease.

What is Lyme disease?

Lyme disease is an infection that people get when they are bitten by deer ticks that carry a certain type of bacteria. The tick is about the size of a poppy seed or sesame seed. It typically must be attached to your skin for at least 36 hours to pass the bacteria to you. Ticks that are attached for less than 24 hours, and those that are not engorged are unlikely to pass the bacteria to you.

Who gets it?

It is most common in people who live in the northeastern or north-central United States, and in people who work or live in areas that have a large deer population. You can get Lyme disease any time of the year, but it most often happens in late spring and early summer.

What are the symptoms?

Lyme disease usually begins as a rash called erythema migrans (er-uh-THEE-muh my-grenz). It typically appears three to 30 days after a tick bite and can be found anywhere on the skin. The rash most often starts as a red spot that grows larger than 5 cm. Sometimes the rash looks like a bull's-eye (i.e., clear in the center).

You may have chills, fatigue, headache, muscle aches, neck stiffness, and joint pain. Some people may also have pain and swelling of the knee, drooping of part of the face, or chest pain. It is important for you to see your doctor if you have any of these symptoms, because they can also be related to other illnesses.

How is it diagnosed?

Your doctor will take a medical history and perform a physical exam. You may also need a blood test. If you have had symptoms longer than six weeks, and your blood test is negative, your symptoms are probably not caused by Lyme disease.

How is it treated?

Most of the time, taking antibiotics for one to three weeks will treat the Lyme disease. Some people with certain heart or nervous system problems caused by Lyme disease may need to be hospitalized.

How can I prevent it?

Be careful when walking in wooded or grassy areas. Wear bug spray, but be sure to read the instructions before using it. Check your skin for ticks, paying close attention to your head, armpits, and groin. If you find a tick, use tweezers to carefully remove it. It also helps to keep your lawn mowed, remove piles of leaves or wood from your yard, install a fence to keep deer out, and spray certain areas with pesticides.

Where can I get more information?

Your doctor

AAFP's Patient Education Resource

American Lyme Disease Foundation

Centers for Disease Control and Prevention

Infectious Diseases Society of America

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