Ticks are small spiderlike insects (arachnids) that bite to fasten themselves onto the skin and feed on blood. Ticks live in the fur and feathers of many birds and animals. Tick bites occur most often during early spring to late summer and in areas where there are many wild animals and birds.

Most ticks do not carry diseases, and most tick bites do not cause serious health problems. But it is important to remove a tick as soon as you find it. Removing the tick's body helps you avoid diseases the tick may pass on during feeding. Removing the tick's head helps prevent an infection in the skin where it bit you. See the Home Treatment section of this topic for the best way to remove a tick.

Usually, removing the tick, washing the site of the bite, and watching for signs of illness are all that is needed. When you have a tick bite, it is important to determine whether you need a tetanus shot to prevent tetanus (lockjaw).

Some people may have an allergic reaction to a tick bite. This reaction may be mild, with a few annoying symptoms. In rare cases, a severe allergic reaction (anaphylaxis) may occur.

Many of the diseases ticks carry cause flu-like symptoms, such as fever, headache, nausea, vomiting, and muscle aches. Symptoms may begin from 1 day to 3 weeks after the tick bite. Sometimes a rash or sore appears along with the flu-like symptoms. Common tick-borne diseases include:

• Lyme disease.
• Rocky Mountain spotted fever.
• Tularemia.
• Ehrlichiosis.
• Relapsing fever.
• Colorado tick fever.
• Babesiosis.

Tick paralysis is a rare problem that may occur after a tick bite. In some parts of the world, tick bites may cause other tick-borne diseases, such as South African tick-bite fever.

Review the Emergencies and Check Your Symptoms sections to determine if and when you need to see a doctor.