Lyme disease: symptoms, rash, testing and prevention

In short

• Lyme disease is a bacterial infection spread by infected blacklegged ticks, which usually have to stay attached for more than 24 hours to pass it on.
• Early signs appear 3 to 30 days after the bite: an expanding red rash called erythema migrans in about 70 to 80 percent of infected people, with or without fever, chills, headache, fatigue and aches.
• The rash is not always a bull's-eye, and it is harder to see on brown or black skin, so any slowly growing patch after a tick bite is worth showing to a clinician.
• Blood tests look for antibodies, which take weeks to appear, so an early test can be negative. A clinician weighs symptoms, tick exposure and results together.
• Antibiotics started early usually bring a quick, complete recovery. Left untreated, the infection can reach the joints, the heart and the nervous system.

What Lyme disease is and where it occurs

In the United States the bacterium behind Lyme disease is usually Borrelia burgdorferi, and it reaches people through the bite of an infected blacklegged tick, also called a deer tick. These ticks are most common in the Northeast, the Mid-Atlantic, the Upper Midwest and northern California.

Ticks wait in grassy, brushy and wooded areas, and blacklegged ticks can bite whenever winter temperatures are above freezing. Not every tick carries the bacteria, and most tick bites do not lead to illness. The bite itself is often painless, and a tick can sit unnoticed in the groin, armpits or scalp.

Symptoms: early and later signs

• Early signs, 3 to 30 days after the bite: fever, chills, headache, fatigue, muscle and joint aches, and swollen lymph nodes. These can occur without any rash.
• The erythema migrans rash typically starts at the bite site after about 7 days, though the range is 3 to 30 days. The NHS notes it can show up as late as 3 months after a bite.
• Later signs, days to months after the bite if untreated: severe headaches and neck stiffness, more rashes on other parts of the body, drooping of the face on one or both sides, and joint pain and swelling, especially in the knees.
• Heart and nerve involvement is less common: heart palpitations or an irregular heartbeat (Lyme carditis), dizziness, shortness of breath, and shooting pain, numbness or tingling in the hands or feet.

What does the rash look like? It spreads slowly over several days and can reach 12 inches (30 cm) or more. It may feel warm but is rarely itchy or painful. Often it clears in the middle, which gives the target look, but the CDC stresses that it does not always appear as a classic bull's-eye.

On white skin the rash looks pink, red or purple. On brown or black skin it is harder to see and may look like a bruise, so check the area after any known tick bite.

Who is at risk

Anyone who spends time in tick habitat can be exposed: hiking, camping, gardening, or playing in a backyard with tall grass or leaf litter. Pets can pick up ticks too, so check them as well as yourself.

The risk rises with the time a tick stays attached. That is why checking for ticks, and removing them promptly, matters more than anything else on this list.

Preventing tick bites

1. Cover up.Wear long sleeves and long pants, light-colored if you can so ticks show up, with trousers tucked into socks. Stay on cleared paths and avoid brush and tall grass.
2. Use repellent.Choose an EPA-registered product containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol or 2-undecanone, and follow the label for how often to reapply. Clothing and gear can also be treated with 0.5% permethrin.
3. Check.Look over your body, clothes, gear and pets during and after time outdoors, including in your own yard. A lint roller can pick up ticks you cannot see.
4. Shower.Shower soon after coming in to wash off ticks that have not attached yet, and launder clothes in hot water.
5. Remove promptly.If a tick is attached, take it off straight away with fine-tipped tweezers or a tick-removal tool, gripping close to the skin and pulling steadily upward, then clean the bite. Do not wait for an appointment.
6. Tidy the yard.Mow the grass, clear leaf litter, trim branches to let in sunlight and keep a barrier of wood chips or gravel about 3 feet wide between lawn and woods.

When to see a doctor

• You were bitten by a tick, or spent time where infected ticks could live, in the past 3 months and now have flu-like symptoms or a round or oval rash.
• A red patch near a bite keeps growing, or new rashes appear elsewhere.
• One side of your face droops, or a knee or another joint becomes swollen and painful.
• You had a tick bite and symptoms such as fatigue and aches last or return.

Start with your primary care provider and mention any time in woods or grass. Tell them if you had a tick bite, even if you are unsure of the date.

Red flags, call 911 now: fainting; chest pain; a racing or irregular heartbeat with shortness of breath; a severe headache with a stiff neck and confusion. Lyme disease can affect the heart and nervous system, and these symptoms need emergency care whatever the cause.

How doctors confirm it

There is no single quick test. A clinician considers your symptoms, how likely you were to meet infected ticks, other illnesses that could explain the picture, and lab results where they are indicated.

Laboratory diagnosis relies on a blood test for antibodies against the bacteria, and two types of blood test are used together. The immune system needs several weeks to make enough antibodies, so early in the illness, even when the rash is present, the result can be falsely negative. FDA-cleared tests are considered reliably sensitive after about 4 to 6 weeks, and your clinician may repeat the test if symptoms continue after a negative result.

A positive antibody test can stay positive for months or years after the bacteria are gone, so on its own it does not prove an infection is active. The CDC advises caution with tests from labs that are not FDA-cleared, and the NHS warns against online tests or treatments with no scientific support. Anaplasmosis is the most common co-infection from the same ticks, and babesiosis is another that needs different medicine.

Treatment in general terms

Lyme disease is treated with antibiotics. Doxycycline, amoxicillin and cefuroxime axetil are the ones the CDC names, and most cases need 10 days to 4 weeks. The choice and length depend on symptoms, age, allergies and pregnancy, so take them only as prescribed by a doctor, and finish the course even if you feel better. Severe cases may need antibiotics through a vein in hospital.

People treated early with appropriate antibiotics usually recover quickly and completely. Some have pain, fatigue or trouble thinking for more than 6 months, known as post-treatment Lyme disease syndrome. No treatment has been proven for it, long-term antibiotics have not helped, and symptoms can be managed with your doctor.

Common misunderstandings

• A tick bite does not automatically mean Lyme disease: the tick must carry the bacteria and, usually, stay attached long enough.
• No bull's-eye does not mean no Lyme disease, because the rash takes many shapes and colors.
• A negative test in the first weeks does not rule it out, and a positive one does not prove the infection is still active.

Questions and answers

Sources

1. CDC — Signs and Symptoms of Untreated Lyme Disease
2. CDC — Testing and Diagnosis for Lyme disease
3. CDC — Treatment and Intervention for Lyme Disease
4. CDC — Preventing Lyme Disease
5. MedlinePlus — Lyme Disease
6. NHS — Lyme disease

Sources checked on 28 October 2026.