Rocky Mountain Spotted Fever

[rŏk'ē moun'tən]

American dog tick

Rocky Mountain spotted fever (RMSF) is spread to people through the bite of an infected tick. Symptoms of RMSF typically begin 3–12 days after the bite and often include sudden onset of headache, fever, stomach and muscle pain, and vomiting. When not treated early, RMSF can get worse very quickly, and can potentially end in death, even in previously healthy people. Because early symptoms are often vague and can resemble so many other diseases, it can be difficult to diagnose.


Key Facts

  • Doxycycline is the treatment of choice for RMSF in adults and children of all ages. It is most effective if started before the 5th day of symptoms.
  • Children <10 years of age are five times as likely to die from RMSF than adults.
  • RMSF can occur during any month, but the majority of cases have an illness onset during the summer months.
  • North Carolina, Oklahoma, Arkansas, Tennessee and Missouri account for over 60% of RMSF cases in the United States.


Man spraying insect repellent

Avoid Tick Bites

Use repellents that contain 20% or more DEET (N, N-diethyl-m-toluamide) on exposed skin for protection that lasts up to several hours. Use products that contain permethrin on clothing.

Woman and dog

Protect Your Pets

Check your pets daily for ticks, especially after they spend time outdoors. If you find a tick on your dog, remove it right away. To prevent ticks from getting on your pets, talk to your veterinarian about the best pesticide product to use.

Symptoms of RMSF

Know the Symptoms

Typical symptoms of RMSF include fever, headache, abdominal pain, vomiting and muscle pain. A rash like the one pictured here may also develop, but is often absent in the first few days, and in some patients, never develops. Never wait for the presence of a rash to suspect RMSF.

Doctor taking woman's temperature

See Your Doctor Right Away

If you develop a fever or rash following potential exposure to ticks see your doctor immediately. Even if it isn’t RMSF, it could also be another tickborne disease. Be sure to mention any history of tick bites, or time spent in tick habitats.

Prevention Tips

  • Use Environmental Protection Agency (EPA)-registered insect repellents containing DEET, picaridin, IR3535, Oil of Lemon Eucalyptus (OLE), para-menthane-diol (PMD), or 2-undecanone on exposed skin.
  • Treat clothing and gear with products containing 0.5% permethrin.
  • Bathe or shower as soon as possible after coming indoors to wash off and more easily find ticks that are crawling on you.
  • Check yourself, your kids, and your pets for ticks daily, especially after they spend time outdoors in areas where ticks may be found.
  • Remove attached ticks as soon as possible. The preferred method of removal is to grasp the tick close to the skin with tweezers or fine-tipped forceps and gently pull upward with constant pressure.

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Page last reviewed: April 9, 2018