Rocky Mountain Spotted Fever


The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What is Rocky Mountain spotted fever?

Rocky Mountain spotted fever (RMSF) is a disease that is caused by infection with a type of bacteria called Rickettsia rickettsi, which is spread through bites from ticks that are infected. 

How common is Rocky Mountain spotted fever in pregnancy?

Tick-borne diseases as a whole affect about 25,000 people each year in the US. The incidence of RMSF has been on the rise in North America since the beginning of this century. In the US, 11 cases of RMSF were reported per 1 million people during 2014. The number of cases is highest in the central-eastern portion of the US and also highest in summer when ticks are most active, although the condition can develop at any time of the year. A particular incidence during pregnancy has not been reported, but pregnant women are often exposed to ticks if they spend time outside, and recently four cases of RMSF were reported in pregnant women in the Sonora region of Mexico.

How is Rocky Mountain spotted fever diagnosed?

RMSF is quite difficult to diagnose. Symptoms of RMSF include fever, rash, headache, nausea, vomiting, muscle pain, abdominal pain, and lack of appetite. Such symptoms occur in numerous diseases, but combined with a history of having been outside in locations where infected ticks may be active could provide physicians with a clue, particularly if tests for more common infectious conditions turn out to be negative, and if a tick bite can be identified on the body. Importantly, the rash develops a few days after infection, consisting of red splotches which look like pinpoint dots. This can be enough of a clue for the doctor to order specialized blood tests that can determine if you have been infected with Rickettsia, particularly R. rickettsia. These tests include polymerase chain reaction (PCR) and antibody tests for the presence of proteins of Rickettsia. 

Does Rocky Mountain spotted fever cause problems during pregnancy?

Pregnant women who develop RMSF will suffer symptoms such as rash, fever, and headache, similar to non-pregnant people, but fever can dehydrate you more easily when you are pregnant. If not treated with the appropriate antibiotic therapy early, RMSF can be fatal. Additionally, symptoms of RMSF may be confused with those of a serious pregnancy complication called preeclampsia.  

Does Rocky Mountain spotted fever during pregnancy cause problems for the baby?

Any fever during pregnancy may increase a babys risk of having congenital defects involving the heart and other organs. Additionally, there have been reports of women with RMSF suffering spontaneous abortion (miscarriage) during the first trimester.

What to consider about taking medications when you are pregnant:

  • The risks to yourself and your baby if you do not treat the RMSF
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat Rocky Mountain spotted fever during pregnancy?

The main treatment for RMSF is the antibiotic doxycycline, which is thought to be fairly safe in pregnancy, although more studies are needed to be certain. The same antibiotic also can be given for the prevention of RMSF and other tick-borne diseases in the event of a tick bite.

For treating the fever itself, there are three main categories of antipyretic (fever-fighting) drugs. One group consists of acetaminophen in the United States and paracetamol in other countries. Another group is called non-steroidal anti-inflammatory drugs (NSAIDs), which include ibuprofen, naproxen, and many others. Along with being antipyretic, NSAIDs also reduce inflammation. The third group, called salicylates, includes aspirin, which technically is also a kind of NSAID, because it reduces inflammation. There is concern that NSAIDs and salicylates may be harmful to the developing baby, but acetaminophen and paracetamol are thought to be safe.

Who should NOT stop taking medication for Rocky Mountain spotted fever in pregnancy?

Pregnant women who need acetaminophen or paracetamol to eliminate fever should not stop taking the medication since the risk of the fever hurting the baby is significant. Everybody with RMSF should continue with antibiotic therapy as directed until the treatment is complete.

What should I know about choosing a medication for Rocky Mountain spotted fever in pregnancy?

You may find Pregistrys expert reports about the individual medications to treat RMSF here. Additional information can also be found in the sources listed at the end of this report.

What should I know about taking a medication for Rocky Mountain spotted fever when I am breastfeeding?

Acetaminophen, paracetamol, NSAIDs, and doxycycline are thought to be relatively safe in mothers who breastfeed.

What alternative therapies exist besides medications to treat Rocky Mountain spotted fever during pregnancy?

You need to stay hydrated and rest when you have RMSF. There is no substitute for antibiotic treatment.

What can I do for myself and my baby when I have Rocky Mountain spotted fever during pregnancy?

Cooperate with your obstetrician and other physicians and take your medication as directed.

Resources for Rocky Mountain spotted fever during pregnancy:

For more information about Rocky Mountain spotted fever during pregnancy, contact (800-994-9662 [TDD: 888-220-5446]) or read the following articles:


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General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

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