What it is

Rocky Mountain spotted fever (RMSF) is a bacterial disease spread through the bite of an infected tick.

Signs and symptoms

Early signs and symptoms are not specific to RMSF (including fever and headache). However, the disease can rapidly progress to a serious and life-threatening illness.

Signs and symptoms can include:

  • Fever
  • Headache
  • Rash
  • Nausea or vomiting
  • Stomach pain
  • Muscle pain
  • Lack of appetite

When to seek medical care‎

If you become ill after having been bitten by a tick, having been in the woods, or in areas with high brush where ticks commonly live, see your healthcare provider.


A rash is a common sign of RMSF. It usually develops 2 to 4 days after fever begins. The look of the rash can vary widely over the course of illness. Some rashes can look like red splotches and some look like pinpoint dots. RMSF is challenging to diagnose since the rash, a common symptom, often appears late in the illness.

Late-stage rash in a patient with Rocky Mountain spotted fever.

Long-term health problems

RMSF does not result in chronic or persistent infections. Some patients who recover from severe RMSF may be left with permanent damage, such as:

  • Amputation of arms, legs, fingers, or toes (from blood vessel damage)
  • Hearing loss
  • Mental Disability

Any permanent damage is caused by the acute illness and does not result from a chronic infection.

How it spreads

Rocky Mountain spotted fever is a serious tickborne illness which can be deadly if not treated early. It is spread by several species of ticks in the United States, including:

RMSF cases occur throughout the United States.

Map of the United States showing where in the US the American Dog Tick is located. The entire eastern half of the country is highlighted.

Estimated geographic distribution of American dog ticks.

Map of the United States showing the approximate distribution of the Rocky mountain wood tick. The area effected is the Northwestern part of the country.

Estimated geographic distribution of Rocky Mountain wood ticks.

Testing and diagnosis

Your healthcare provider may order certain blood tests to look for evidence of RMSF. The results of these tests can take weeks. If your healthcare provider thinks your illness might be RMSF, they should recommend antibiotic treatment before test results are available.

Treatment and recovery

RMSF can be life-threatening. Early treatment with the antibiotic doxycycline can prevent death and severe illness. It is approved for adults and children of all ages.

Doxycycline saves lives banner.  Doxycycline is the number 1 recommended treatment for suspected rickettsial infections in patients of all ages.

Doxycycline is the recommended antibiotic treatment for RMSF.