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Mefloquine Pregnancy and Breastfeeding Warnings

Mefloquine is also known as: Lariam

Mefloquine Pregnancy Warnings

Mefloquine has been assigned to pregnancy category B by the FDA. Animal studies have revealed evidence of embryotoxicity and teratogenicity. Data from published studies in pregnant women have shown no increase in the risk of teratogenic effects or adverse pregnancy outcomes following mefloquine treatment or prophylaxis during pregnancy. Mefloquine is only recommended for use during pregnancy when benefit outweighs risk. Malaria in pregnant women may be more severe than in nonpregnant women and has resulted in abortion, stillbirth, and prematurity. Women of childbearing age who are traveling to endemic malarious areas should be warned against becoming pregnant and to use effective contraception during mefloquine prophylaxis and for up to 3 months afterwards. However, unplanned pregnancy during mefloquine use is not an indication for terminating the pregnancy.

Published data on mefloquine use during pregnancy include randomized controlled trials, intervention trials, prospective and retrospective cohort studies, and case series. These data showed that pregnant women who took mefloquine at various doses for both prevention and treatment of malaria did not have an increased risk of teratogenic effects or adverse pregnancy outcomes compared to the background rate in the general population. These data include more than 700 first trimester exposures to mefloquine and over 2000 second and third trimester exposures. The Centers for Disease Control and Prevention (CDC) consider chloroquine to be the drug of choice for malaria prophylaxis during pregnancy for women traveling to areas where chloroquine-resistant Plasmodium falciparum has not been reported. For travel to areas where chloroquine resistance is present, mefloquine is the only medication recommended by the CDC for malaria prophylaxis during pregnancy.

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Mefloquine Breastfeeding Warnings

The Centers for Disease Control and Prevention state that because mefloquine may be safely prescribed to infants, it is also safe for infants to be exposed to the small amounts excreted in breast milk. The quantity of mefloquine transferred in breast milk is insufficient to provide adequate protection against malaria.

Mefloquine is excreted into human milk. Three to four percent of a dose is excreted into milk. The manufacturer recommends that caution be used when administering mefloquine to nursing women.

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References for pregnancy information

  1. Briggs GG, Freeman RK, Yaffe SJ.. "Drugs in Pregnancy and Lactation. 5th ed." Baltimore, MD: Williams & Wilkins (1998):
  2. Bangchang KN, Davis TME, Looareesuwan S, White NJ, Bunnag D, Karbwang J "Mefloquine pharmacokinetics in pregnant women with acute falciparum malaria." Trans R Soc Trop Med Hyg 88 (1994): 321-3
  3. Freedman DO "Clinical practice. Malaria prevention in short-term travelers." N Engl J Med 359 (2008): 603-12
  4. Samuel BU, Barry M "The pregnant traveler." Infect Dis Clin North Am 12 (1998): 325
  5. CDC. Centers for Disease Control and Prevention "Guidelines for Treatment of Malaria in the United States. Available from: URL:" ([2013, Jul 01]):
  6. "Recommendations for the prevention of malaria among travelers." MMWR Morb Mortal Wkly Rep 39 (1990): 1-10
  7. "Product Information. Lariam (mefloquine)." Roche Laboratories, Nutley, NJ.
  8. Nosten F, Vincenti M, Simpson J, Yei P, Thwai KL, deVries A, Chongsuphajaisiddhi T, White NJ "The effects of mefloquine treatment in pregnancy." Clin Infect Dis 28 (1999): 808-15
  9. Subramanian D, Moise KJ Jr, White AC Jr "Imported malaria in pregnancy: report of four cases and review of management." Clin Infect Dis 15 (1992): 408-13
  10. Arguin PM, Mali S, CDC. Centers for Disease Control and Prevention "Infectious diseases related to travel. Malaria. Available from: URL:" ([2011 Nov 08]):

References for breastfeeding information

  1. Edstein MD, Veenendaal JR, Hyslop R "Excretion of mefloquine in human breast milk." Chemotherapy 34 (1988): 165-9
  2. Arguin PM, Mali S, CDC. Centers for Disease Control and Prevention "Infectious diseases related to travel. Malaria. Available from: URL:" ([2011 Nov 08]):
  3. "Product Information. Lariam (mefloquine)." Roche Laboratories, Nutley, NJ.

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