Ticks are common in the United States. They live outdoors in:

• grass
• trees
• shrubs
• leaf piles

They’re attracted to people and their four-legged pets, and they can easily move between the two. If you’ve spent any time outdoors, you’ve likely encountered ticks at some point.

Tick bites are often harmless, in which case they don’t cause any noticeable symptoms. However, ticks can cause allergic reactions, and certain ticks can pass diseases onto humans and pets when they bite. These can be dangerous or even deadly.

Learn how to recognize ticks, the symptoms of tick-borne illnesses, and what to do if a tick bites you.

Ticks are small, blood-sucking bugs. They can range in size from as small as a pin’s head to as large as a pencil eraser. Ticks have eight legs. They’re arachnids, which means they’re related to spiders.

The different kinds of ticks can range in color from shades of brown to reddish brown and black.

As they take in more blood, ticks grow. At their largest, ticks can be about the size of a marble. After a tick has been feeding on its host for several days, they become engorged and can turn a greenish-blue color.

Ticks prefer warm, moist areas of the body. Once a tick gets on your body, they’re likely to migrate to your armpits, groin, or hair. When they’re in a desirable spot, they bite into your skin and begin drawing blood.

Unlike most other bugs that bite, ticks typically remain attached to your body after they bite you. If one bites you, you’ll likely know because you’ll have found a tick on your skin. After a period of up to 10 days of drawing blood from your body, an engorged tick can detach itself and fall off.

What are the symptoms of a tick bite?

Tick bites are usually harmless and may produce no symptoms. However, if you’re allergic to tick bites, you may experience:

• pain or swelling at the bite site
• a rash
• a burning sensation at the bite site
• blisters
• difficulty breathing, if severe

Some ticks carry diseases, which can be passed on when they bite. Tick-borne diseases can cause a variety of symptoms and usually develop within several days to a few weeks after a tick bite. Potential symptoms of tick-borne diseases include:

• a red spot or rash near the bite site
• a full body rash
• neck stiffness
• a headache
• nausea
• weakness
• muscle or joint pain or achiness
• a fever
• chills
• swollen lymph nodes

Be sure to seek medical attention as soon as possible if bitten by a tick in order to be evaluated for any potential treatment.