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.

Tetracyclines can cause permanent discoloration of your baby’s teeth when taken during the second and third trimesters of pregnancy. They should not be used during pregnancy unless your doctor determines that they are medically necessary.

What are tetracyclines?

Tetracyclines are a group of antibiotics used to treat infections caused by bacteria. They can also be used to help reduce acne. Types of tetracyclines that are available include: doxycycline, minocycline, tetracycline, and demeclocycline. These medications are only available by prescription from your doctor.

What are tetracyclines used to treat?

Tetracyclines are used to treat many different types of bacterial infections and can also be used to treat severe acne. Tetracyclines are effective against many urinary, skin, respiratory, and eye infections. They can also be used to treat ulcers and sexually transmitted infections. In addition, tetracyclines are effective against many diseases that are spread by ticks, mice, or other animals.

How do tetracyclines work?

Tetracyclines work by preventing bacteria from growing and reproducing. They should not be taken with food or with any supplements containing iron, calcium, zinc, or magnesium.

If I am taking a tetracycline antibiotic, can it harm my baby?

The FDA warns that tetracycline antibiotics can cause harm to your baby and should not be used during pregnancy unless your doctor determines that they are absolutely necessary. These drugs should especially be avoided during the second and third trimesters of pregnancy. When given to premature babies, tetracyclines have been found to reduce the growth rate of calf bones. Animal studies have shown that tetracyclines cross the placenta and can cause harmful effects to the developing offspring, such as interfering with bone development. In addition, when tetracyclines are used during the second half of pregnancy (at around 5 or 6 months of pregnancy and later), they cause permanent discoloration of your baby’s teeth. Tetracyclines bind to calcium and become integrated into the baby’s developing bones and teeth, which causes the discoloration. There have also been reports of cavities and defects in the baby’s tooth enamel when tetracyclines were used during pregnancy. However, it was later determined that these effects were not related to the use of tetracyclines. Furthermore, tetracyclines can cause a type of liver disease in expecting moms which can lead to premature birth or death of the baby in the womb.

Tetracyclines may increase the risk of certain types of birth defects, although the exact effect of these medications is unknown. A review found that the use of oxytetracycline (a tetracycline that is no longer available in the U.S.), resulted in a higher incidence of neural-tube defects, cleft palate (a birth defect in the baby’s mouth), and other birth defects. However, the results were based on a limited number of reports (2 neural tube defects, 2 cleft palates, and 4 other defects). Another study found that the use of tetracycline during pregnancy was associated with minor birth defects, such as inguinal hernia, hypospadias (a birth defect in the urinary tract of baby boys), and a defect in the development of the baby’s limbs. A few cases of inguinal hernia and clubfoot (defects in the baby’s foot) were reported with the use of demeclocycline during pregnancy. The same study reported that the use of oxytetracycline during pregnancy was associated with major birth defects. Although some reports have found that there may be a risk of birth defects when tetracyclines are used during pregnancy, the data is very limited and other studies have not found an increased risk. A review that looked at Tennessee Medicaid data found that doxycycline was unlikely to result in a higher risk of birth defects. 

Bottom line: Tetracyclines can cause harm to your baby and should be avoided during pregnancy. When used during the second and third trimesters of pregnancy, they cause permanent discoloration of your baby’s teeth.

If I am taking a tetracycline antibiotic and become pregnant, what should I do?

If you become pregnant while taking a tetracycline antibiotic, you should contact your doctor immediately. These medications can cause harm to your baby and are not recommended for use during pregnancy. Your doctor may decide to discontinue the tetracycline antibiotic and prescribe a safer alternative.

If I am taking a tetracycline antibiotic, can I safely breastfeed my baby?

Tetracyclines pass into breast milk and have the potential to cause serious harm to the breastfed baby. They can theoretically cause dental staining and prevent proper bone growth in breastfed babies. The FDA recommends that either nursing should be discontinued, or the tetracycline antibiotic should be discontinued prior to breastfeeding. Despite the FDA’s recommendation, the American Academy of Pediatrics has classified tetracycline as usually compatible with breastfeeding. Tetracyclines have not been associated with any side effects in breastfed babies. Calcium in breast milk prevents the absorption of tetracyclines in breastfed babies, meaning that babies absorb minimal amounts of the medications. Consequently, short-term use of tetracyclines is unlikely to harm the breastfed baby. In addition, despite the potential risks to the baby, dental staining has never been reported from exposure to tetracyclines in breast milk.

Bottom line: Tetracyclines should be avoided during nursing unless your doctor determines that they are medically necessary. Despite the lack of available evidence, these medications have the potential to cause permanent dental staining and disrupt proper bone development in your baby.

If I am taking a tetracycline antibiotic, will it be more difficult to get pregnant?

There have been no studies looking at the effects of tetracyclines on fertility in women, but one study found that treatment with doxycycline could improve fertility in some men. The study showed that doxycycline improved a condition where men have an unusually high number of white blood cells in their semen. These men also had improved fertility after taking doxycycline. In addition, women who are taking a tetracycline antibiotic with oral contraceptives should contact their doctor because tetracyclines can cause oral contraceptives to be less effective.

If I am taking a tetracycline antibiotic, what should I know?

Tetracyclines should not be used during pregnancy unless your doctor determines that they are medically necessary. They can cause permanent discoloration of your baby’s teeth. They may also increase the risk of birth defects or cause abnormalities in the development of your baby’s bones. Tetracyclines should also be avoided during breastfeeding. While there is no evidence that these medications cause harm to the breastfed baby, they have the potential to cause dental staining and decreased bone growth.

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

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

You may find Pregistry's expert reports about individual infections here.  Additional information can also be found in the links below. 

Resources for tetracycline antibiotics during pregnancy and breastfeeding:

For more information about tetracyclines during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or check the following links:

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Last Updated: 07-09-2018
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.