How Safe Are Common Over-the-Counter Pain Killers While Pregnant?

OTC pregnant

In addition to being prudent about which herbs and supplements you take while pregnant, it also pays to be cautious about common over-the-counter (OTC) medications, including OTC painkillers. Here are some common painkillers that you should use with caution.


Aspirin, one of the oldest and most ubiquitous painkillers around, is thought to be safe at low doses (60-100 mg/day). Aspirin is recommended for some pregnant women since several studies have shown that it may reduce the incidence of preeclampsia, intra-uterine growth restriction, and recurrent pregnancy loss. However, full-dose aspirin should only be used when necessary, as it has been associated with harmful effects to the fetus. In the first trimester these may include:

  • Miscarriage
  • Gastroschisis (a disorder whereby the baby’s intestines (and sometimes stomach and liver) protrude outside of the baby’s body through a hole in the belly button)
  • Cleft palate

In the third trimester these may include:

  • Increased risk of bleeding in the brains of premature babies
  • Blood clotting problems for newly born babies
  • Increased risk of hypertension in newly born babies
  • Blood clotting problems in the mother


Another commonly used OTC painkiller is acetaminophen (also known as paracetamol). Acetaminophen is generally considered to be safe during pregnancy when used sparingly. However, in a recent study of mice, prolonged use of acetaminophen (7 days) was found to reduce testosterone production in the womb by 45%. Low levels of testosterone in the womb have been linked to an increased risk of infertility, testicular cancer, and undescended testicles. The latter outcome was independently confirmed by a large study of 47,400 baby boys which found that acetaminophen taken for longer than 4 weeks, especially during the first and second trimesters, increases the risk of undescended testes.


Non-steroidal anti-inflammatory drugs (NSAIDs) are also popular drugs for pain relief and are used for their anti-inflammatory properties. However, they have a long half-life, cross the placenta easily, and should be avoided whenever possible during pregnancy.

In particular, NSAIDs should be used sparingly:

  • In the first trimester, as they are associated with increased risk of miscarriage
  • In the third trimester, as they can reduce fetal urine output which can lead to a condition called oligohydramnios (reduced amniotic fluid) which can in turn lead to fetal abnormalities
  • After the 32nd week of pregnancy, due to an increased risk of premature closing of the ductus arteriosus

In one large study, women who took any type or dose of NSAID during the first 20 weeks of pregnancy had a 2.4 times higher risk of miscarriage than women who did not take an NSAID. Diclofenac was associated with the highest risk of miscarriage and rofecoxib was associated with the lowest risk. Following exposure in the womb, NSAIDs have been linked to fetal and neonatal adverse effects affecting the:

  • Cardiovascular system
  • Kidney
  • Brain
  • Lung
  • Skeleton
  • Gastrointestinal tract

NSAIDs have also been found to increase the risk of pulmonary hypertension in newborns.

In conclusion, it appears that occasional use of acetaminophen or aspirin is safe during pregnancy. NSAIDs, however, should be avoided as much as possible due to being associated with serious side effects to your baby.

Melody Watson
Melody Watson holds Bachelors degrees in Biochemistry and Microbiology. She works as a medical writer for a medical communications agency in Berlin, Germany, where her work ranges from medical translation to writing publications for medical journals. Melody is passionate about promoting science, including evidence-based medicine, and debunking pseudoscience.

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