Is That a Tick Bite?

May 7th 2016

Most people find ticks while the insect is still biting them, but rashes and other symptoms can be used to confirm a diagnosis. If you think you may have been infected with a tick-borne disease, contact your doctor as soon as possible.

Finding the Tick

The most reliable way to diagnose a tick bite is to find the insect still attached. Ticks are slow feeders that may remain attached to their hosts for several days if they are left undisturbed. This usually makes it easy to diagnose tick bites, because the bug becomes more obvious as it becomes more engorged with blood.

Ticks can only insert their head into skin, so their enlarged bodies are often more visible. Completely encrusted bumps are unlikely to be caused by ticks, unless the patient found a tick there previously and did not remove it properly. In that case, the tick's head might have remained embedded in the skin to cause a mild infection.

Secondary Rashes

Tick bites can sometimes cause secondary reactions. Some people who have previously been bitten experience an itchy sensation and redness or swelling at the site of the tick bite. This is an immune response to tick saliva. However, this is an unpredictable reaction, and many people do not experience it even after multiple bites.

Tick-borne diseases often leave physical indications at the site of the original bite. Lyme disease is known for its distinctive bull's-eye rash, which appears as concentric round rings of red, irritated flesh radiating out from the bite. Rocky Mountain spotted fever often shows up as an asymmetrical rash of red bumps extending from the bite. Some other diseases, such as tularemia, cause an ulcer where the bite occurred. These, along with other symptoms, can be used to diagnose a tick bite.

Geographic Area and Symptoms

Some tick-borne diseases have no symptoms around the site of the original bite, and even those that do may have atypical symptoms where no visible reaction occurs. In this case, the best way to diagnose a tick bite is to consider the patient's exposure risk and symptoms. A person who was recently hiking in an area where Lyme disease is common and has flu-like symptoms should probably be tested for Lyme disease, even if no ticks or rash are found.

More specific diagnostic tests can follow the Lyme disease test. Most tick-borne diseases can be detected using blood tests or other diagnostics. This is the most reliable way to confirm a tick-borne disease.


Tick bites are usually harmless and leave no lasting effects, but they can sometimes transmit serious diseases. These include Lyme disease, Rocky Mountain spotted fever and ehrlichiosis. Diagnosing a tick bite can be difficult because a normal bite has few symptoms, but there are some ways to rule out other potential causes.

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