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.


Chlorpheniramine is considered an antihistamine of choice during pregnancy. There is limited safety information from human studies that have looked at the use of chlorpheniramine during pregnancy, but available studies indicate that there is probably not an increased risk of birth defects. Nursing infants exposed to chlorpheniramine are at risk of drowsiness or irritability; use of this medication while breastfeeding may or may not be recommended. This medication should be used with caution if administered in pregnant women or nursing mothers.

What is chlorpheniramine?

Chlorpheniramine is a first generation antihistamine medication taken to control the symptoms of allergies in children and adults. Chlorpheniramine is currently available as generic and brand name medications, and is available in liquid, syrup, tablet, and extended release tablet to be taken once every 4-6 hours or once every 12 hours for extended release tablets. It is available as an over-the-counter or prescription medication.

What is chlorpheniramine used to treat?

Chlorpheniramine is used to treat allergy symptoms including sneezing, runny nose, itchy nose or throat, itchy skin, and watery eyes in adults and children over 6 years of age.

How does chlorpheniramine work?

Chlorpheniramine works by preventing histamine from binding to receptors on cells in the respiratory tract, gastrointestinal tract, or blood vessels. Interruption of histamine binding prevents the inflammation and activation of the immune system that causes allergy symptoms. First generation antihistamines such as chlorpheniramine can cause drowsiness or sleepiness. 

If I am taking chlorpheniramine, can it harm my baby?

Chlorpheniramine is considered the antihistamine of choice during pregnancy by the American Congress of Obstetricians and Gynecologists (ACOG) and the American College of Allergy, Asthma and Immunology (ACAAI). Available studies have not shown an increase risk of birth defects with chlorpheniramine use during pregnancy.

Evidence from animal studies with chlorpheniramine:

When given to pregnant mice, birth defects were not detected. In pregnant mice given 65 to 650 times the recommended human dose, fetal death occurred.

Evidence from human studies with chlorpheniramine:

The Boston Collaborative Drug Surveillance Program evaluated 275 infants exposed to chlorpheniramine during the first trimester of pregnancy, finding no increased risk of birth defects with in utero exposure. Data from the Swedish Medical Birth Registry found women exposed to antihistamines during pregnancy had a similar rate of birth defects as the general population. The study suggests antihistamine exposure during pregnancy may slightly decrease the risk of heart defects, premature birth, and low birth weight. The Collaborative Perinatal Project identified an increased risk of birth defects such as polydactyly, eye and ear defects, hip dislocation, and genital defects with first trimester chlorpheniramine exposure, but later found the true risk of these birth defects from chlorpheniramine to be unknown. There was, however, an increased risk of inguinal hernia or hernia of the groin. The National Birth Defects Prevention Study reported weak associations between cleft palate and spina bifida and exposure to chlorpheniramine anywhere from one week before conception to the first trimester of pregnancy. The Slone Epidemiology Centers Birth Defects Study found an increased risk of brain and spine defects as well as heart defects in babies exposed to chlorpheniramine. There have been reports of retrolental fibroplasia, an eye disorder causing blindness, with antihistamine use 2 weeks before delivery in premature newborns. 

Bottom line: Chlorpheniramine is an antihistamine of choice during pregnancy. Human studies suggest chlorpheniramine does not increase the risk of birth defects.

If I am taking chlorpheniramine and become pregnant, what should I do?

If you are taking chlorpheniramine and become pregnant, you should contact your doctor immediately. Your doctor will determine if your medication is medically necessary, or if it should be discontinued until after the birth of your baby.

If I am taking chlorpheniramine, can I safely breastfeed my baby?

The World Health Organization recommends that women taking chlorpheniramine avoid breastfeeding their babies. Case reports showed drowsiness in nursing infants exposed to this medication. Nursing infants exposed to chlorpheniramine should be monitored for signs of drowsiness or irritability. Premature newborns and infants may be at a higher risk of developing negative side effects with chlorpheniramine exposure. Women who are breastfeeding infants and require an antihistamine are generally advised to take a second generation antihistamine. Occasional dosing of chlorpheniramine at night after the last breastfeed of the day may decrease the risk of any negative side effects in nursing infants. Chlorpheniramine may decrease milk production particularly if taken before lactation is established in new mothers, or if high doses are administered to nursing women. It is important to weigh the risks versus benefits before taking this medication while nursing an infant. 

Bottom line: Breastfeeding is generally considered safe in women who are taking chlorpheniramine, but organizations such as the World Health Organization recommend against breastfeeding due to limited availability of safety information in nursing infants. In breastfeeding moms taking this medication, monitoring for drowsiness and irritability in babies is advised.

If I am taking chlorpheniramine, will it be more difficult to get pregnant?

Possibly if your male partner is taking it. Laboratory studies suggest chlorpheniramine may negatively affect human sperm motility.

If I am taking chlorpheniramine, what should I know?

Chlorpheniramine is considered compatible with pregnancy. Human studies suggest there is probably no increased risk of birth defects with first trimester exposure to this medication.

Breastfeeding may or may not be recommended in women who are breastfeeding infants due to the potential risk of drowsiness and irritability.

If I am taking any medication, what should I know?

This report provides a summary of available information about the use of chlorpheniramine during pregnancy and breastfeeding. Content is from the product label unless otherwise indicated.

You may find Pregistry's expert report about allergic rhinitis here, reports about various other health conditions as well as the individual medications used to treat allergies and other conditions here.   Additional information can also be found in the resources below. 

For more information about chlorpheniramine during and after pregnancy, contact (800-994-9662 [TDD: 888-220-5446]) or check the following link:

WebMD: Chlorpheniramine

Read the whole report
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.