Medications That You Should Avoid During Pregnancy

As parents, the most important job you have is to keep your baby safe and healthy! This is relevant once your baby is born, but it is just as important while your baby is growing and developing in the womb. Just as there are several nutrients and vitamins that you should consume to keep yourself and your baby safe and healthy, there are also certain things you should avoid consuming. This includes certain medications that you should avoid during your pregnancy since they can negatively impact your developing baby. Although it is quite hard to know which medications are harmful to a fetus since it is not ethical to test medications on pregnant women, there are still some medications that we now know that pregnant women should avoid. 

In this article, we will provide you with information about what some of these medications are and give you a better understanding of why they can be harmful to your fetus. However, keep in mind that the list of medications to avoid is long and that we can’t mention all of them in this article. Therefore, it is important to always talk to your doctor before you start taking any medications while pregnant.

Why is the fetus susceptible to certain medications?

Let’s start with a general explanation of why some medications can be especially harmful to your fetus. Simply put, this is because your fetus is constantly developing into a functional human being in your womb. All the organs and body parts like the legs and arms of the baby are constantly developing and certain toxic substances can stop this development from occurring. This can in turn result in birth defects of your baby and it is therefore very important to avoid intake of such substances.

Common medications to avoid

As mentioned, the list of medications to avoid during pregnancy is long. However, below we have prepared a list of commonly used medications that you should avoid during your pregnancy and how these medications can harm your fetus.

  • Antibiotics: Even though some antibiotics are safe to use during pregnancy, certain antibiotics can cause harm to the fetus. This includes a group called tetracyclines that can affect bone development and discolour a developing baby’s teeth. Another group of antibiotics called sulfonamides might increase the risk of heart conditions, cleft lip or palate, and jaundice in the baby.
  • Ibuprofen: Medications that contain ibuprofen (like Nurofen and Motrin) are some of the most used medications to relieve fever, inflammation, and pain. However, higher doses of ibuprofen can harm the fetus in several ways. Taking ibuprofen during the later stages of pregnancy has for instance been linked to a low level of amniotic fluid and heart defects in the developing fetus. High doses of ibuprofen can also cause premature closing of the fetal ductus arteriosus, which is an important blood vessel in the fetal heart. Even though many experts agree that smaller doses of ibuprofen are probably safe to use in early pregnancy, it is important that you discuss this with your doctor.
  • Warfarin: The blood-thinning substance warfarin is found in the medication Coumadin, and it is used to prevent and treat blood clots. Warfarin can cause what is known as “fetal warfarin syndrome” which is characterised by nasal hypoplasia and skeletal abnormalities including short limbs. 
  • Antiepileptic drugs: This group of drugs is used to treat epilepsy, anxiety, and other mental health disorders. Antiepileptics like clonazepam (brand name Klonopin) and lorazepam (brand name Ativan) can for instance cause withdrawal symptoms in a newborn baby.
  • Antidepressant drugs: Although several antidepressant drugs are considered safe to use during pregnancy, there are still some drugs in this category that should be avoided. This includes the drug Paxil that has been linked to defects of the fetal heart. 
  • ACE-inhibitors: ACE-inhibitors such as Lisinopril or Enalapril are drugs commonly prescribed for high blood pressure. They work by impacting a system in the body called the “Renin-Angiotensin-Aldosterone System” (RAAS) which is essential for the regulation of blood pressure and fluid balance. However, if these drugs are used during the second and third trimesters of pregnancy, they can cause low levels of amniotic fluid, and this can prevent fetal lung development and therefore cause breathing problems in the baby at delivery. 

A word about over the counter (OTC) medications

Except for the medications that require a prescription, several medications can be bought over the counter in pharmacies or supermarkets. If you are pregnant or trying to become pregnant, it is important that you talk to your doctor or a pharmacist before taking any of these medications as well. This includes medication used to treat the common cold, cough, diarrhoea, constipation, nausea and so on. Some of these are totally fine to use during pregnancy but to make sure that is the case it is always recommended that you consult a pharmacist or your doctor about this.

Other substances to avoid 

Apart from the medications mentioned above, several other substances are important to avoid during pregnancy. We can’t list all these substances here, but we would like to bring awareness to two common substances that should be avoided at all costs. These are alcohol and nicotine.

  • Alcohol: This highly consumed substance is broken down more slowly in a fetus and can therefore cause damage to the fetus. The fetal defects that can result from the mother drinking alcohol are called “fetal alcohol syndrome”. This syndrome is characterized by facial malformations, growth retardation and abnormalities of the central nervous system (CNS). Women are therefore strongly urged to not drink alcohol during pregnancy. 
  • Nicotine: Nicotine is a substance found in cigarettes and is known to be harmful to a fetus. There are also other toxic substances in cigarettes, but it is known that nicotine constricts blood vessels including placental blood vessels, and therefore reduces the blood flow to the fetus through the umbilical cord. This will cause less distribution of both nutrients and oxygen to the fetus, and this can result in birth defects such as low birth weight and defects to the brain and lungs of the fetus. Therefore, it is highly recommended that you quit smoking both for the sake of your own health and the health of your unborn baby.  


As we can see, several medications and substances should be avoided during pregnancy since they can cause harm to the fetus. We have mentioned some of these in this article, but several others should be avoided as well. It is therefore important to always consult your doctor or a pharmacist before you start taking any medication during pregnancy. If you need medication for a common cold or the like, your doctor or a pharmacist can also give you advice on which medications are safe for your growing baby! 

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