Merck Manual

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Tick Bites


Robert A. Barish

, MD, MBA, University of Illinois at Chicago;

Thomas Arnold

, MD, Department of Emergency Medicine, LSU Health Sciences Center Shreveport

Last full review/revision May 2020| Content last modified May 2020
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Topic Resources

Ticks, like mites, are closely related to spiders. These small creatures, sometimes carried as parasites on the bodies of humans and animals, may transmit disease to humans.

Ticks can carry many diseases. For example, deer ticks may carry the bacteria that cause Lyme disease or the protozoa that cause babesiosis. Other types of ticks may carry the bacteria that cause Rocky Mountain spotted fever or ehrlichiosis.

The bites of pajaroello ticks, which are present in Mexico and the southwestern United States, produce pus-filled blisters that break, leaving open sores that develop thick black scabs (eschars).

Most tick bites do not transmit disease and are painless. However, they often cause a red bump and itching at the site of the bite and may cause allergic skin reactions in some people.

Deer Ticks

Deer Ticks

Tick paralysis

In North America, some tick species secrete a toxin in their saliva that causes tick paralysis. A person with tick paralysis feels weak and fatigued. Some people become restless, weak, and irritable. After a few days, a progressive paralysis develops, usually moving up from the legs. The muscles that control breathing also may become paralyzed.

Tick paralysis is cured rapidly by finding and removing the tick or ticks. If breathing is impaired, oxygen therapy or a mechanical ventilator may be needed to assist with breathing.


  • Removal of tick

  • Application of antiseptic

  • Sometimes an antibiotic by mouth to prevent Lyme disease

Tick bites can sometimes be prevented by taking precautions in areas where ticks are common (see Figure: Preventing Tick Bites).

Tick removal should be done as soon as possible. Removal is best accomplished by grasping the tick with curved tweezers as close to the skin as possible and pulling it directly out. The tick’s head, which may not come out with the body, should be removed, because it can cause prolonged inflammation. Most of the folk methods of removing a tick, such as applying alcohol, fingernail polish, or petroleum jelly or using a hot match, are ineffective and may cause skin damage or cause the tick to expel infected saliva into the bite site.

Did You Know...

  • The best way to remove a tick is with tweezers, directly pulling it off.

After the tick is removed, an antiseptic should be applied. If swelling and discoloration are present, an oral antihistamine may be helpful. If the tick appears to have been attached for an extended period (the tick is very swollen) or Lyme disease is prevalent in the area, doctors may give an antibiotic to help prevent Lyme disease.

If a tick bite, such a pajaroello tick bite, causes significant skin damage, the doctor extensively cleans and removes any dead skin from the wound. The doctor may apply corticosteroids and antiseptics to the area to prevent further skin damage and infection.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
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