Acetaminophen and Aspirin (Buffered)

Applies to acetaminophen / aspirin: oral packet, oral tablet

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Belly pain or heartburn.
• Upset stomach.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at http://www.fda.gov/medwatch.

Acetaminophen has not been formally assigned to a pregnancy category by the FDA. It is routinely used for short-term pain relief and fever in all stages of pregnancy. Acetaminophen is believed to be safe in pregnancy when used intermittently for short durations. Acetaminophen should only be given during pregnancy when need has been clearly established. Aspirin has not been formally assigned to pregnancy category by the FDA. However, aspirin is considered to be in pregnancy category D by the FDA if full dose aspirin is taken in the third trimester. Use of nonsteroidal anti-inflammatory drugs during the third trimester of pregnancy should be avoided due to effects on the fetal cardiovascular system (closure of the ductus arteriosus). Aspirin use in pregnancy has been associated with alterations in both maternal and fetal hemostasis. In addition, high doses have been associated with increased perinatal mortality, intrauterine growth retardation, and teratogenic effects. During the first two trimesters of pregnancy, aspirin should only be given during pregnancy when clearly needed and when benefit outweighs risk. In 1990, the FDA issued a warning that it is especially important not to use aspirin during the last trimester of pregnancy unless specifically directed to do so by a physician because it may cause problems in the unborn child or complications during delivery.

Two cases of acetaminophen overdose in late pregnancy have been reported. In both cases neither the neonate nor the mother suffered hepatic toxicity. Investigations have revealed conflicting results with regards to the pharmacokinetic disposition of acetaminophen in pregnant women. One study has suggested that the oral clearance of acetaminophen is 58% higher and the elimination half-life is 28% longer in pregnant women compared to nonpregnant women. Another study has suggested that the elimination half-life is not different in patients who are pregnant. That study also suggested that the volume of distribution of acetaminophen may be higher in pregnant women. One study has suggested that acetaminophen in typical oral doses may result in a reduced production of prostacyclin in pregnant women. That study also suggested that acetaminophen does not affect thromboxane production. Increased maternal bleeding can occur during delivery when aspirin is used 1 week prior to and/or during labor and delivery. Prolonged gestation and labor have been reported due to aspirin's inhibition of prostaglandin. A study of the use of low-dose aspirin (60 mg per day) to prevent and treat preeclampsia in 9364 pregnant women (the Collaborative Low-dose Aspirin Study in Pregnancy--CLASP) did "not support routine prophylactic or therapeutic administration of antiplatelet therapy in pregnancy to all women at increased risk of preeclampsia or IUGR." In that study, no excess of intraventricular hemorrhage, neonatal bleeds, or mortality attributable to bleeding were observed. The investigators did identify a possible role for low-dose aspirin in the treatment of early- onset preeclampsia severe enough to need very preterm delivery. Another study of low-dose aspirin (follow-up from the Italian Study of Aspirin in Pregnancy) has suggested that "low dose aspirin in pregnancy is safe with respect to the risks of malformation and of major impairment in development at 18 months of age." High-dose aspirin (2 g per day) has been associated with stillbirths, cerebral hemorrhage, oculoauriculovertebral dysplasia, neonatal salicylate toxicity, constricted ductus arteriosus, cyclopia, and neonatal acidosis. Some cases of congenital heart defects have been reported. However, a case control study of aspirin use in the first trimester concluded that aspirin "does not increase the risk of congenital heart defects in relation to that of other structural malformations."