What medications are safe/dangerous during pregnancy?

During the 40 weeks of pregnancy, common ailments may arise, but the available medications are limited due to safety concerns.

Some medications may could cause harm by interfering with embryo development, damaging the foetus’s organs, increasing the risk of miscarriage or damaging the placenta. Any of these scenarios could potentially put your baby’s life at risk.

So how can pregnant women manage common ailments without harming their baby? Understanding which medications are safe or dangerous is crucial.

What common ailments do pregnant women get?

The hormonal changes and extra body strain during pregnancy can make pregnant women more prone to a number of common ailments, including:

  • pain (eg. lower back pain)
  • constipation
  • heartburn/ acid reflux
  • nausea and vomiting (morning sickness)
  • vaginal thrush

Treatment options for common ailments in pregnancy


Allergies are most commonly treated with antihistamines. Luckily, antihistamine use has not been associated with increased risk of foetal harm.

There are two generations of antihistamine medications. The first generation is more sedating than the second generation. It is generally recommended for pregnant women because these medications have been used for longer. As a result, more safety data is available.

Having said that, it is important to note that using large doses of sedating antihistamines near term may lead to tremor, irritability and poor feeding.

Pain and migraine

Pain is a common complaint during pregnancy, commonly due to the heavy strain on a woman’s lower back. For mild to moderate pain relief, paracetamol is the preferred medication choice.

For severe pain, the lowest effective dose and shortest duration of opioid medications may be used with extreme caution. This is because opioid painkillers are associated with multiple complications, including:

  • heart and neural tube defects when used in early pregnancy
  • respiratory depression and withdrawal symptoms with chronic use
  • neonatal abstinence syndrome (symptoms include gastrointestinal dysfunction, poor feeding, vomiting, poor weight gain and many more)

Non-steroidal anti-inflammatory drugs (NSAIDs) are also commonly used to manage pain, including the well-known aspirin and ibuprofen (Neurofen). Importantly, these medications are NOT recommended during pregnancy as they have been associated with an increased risk of spontaneous abortion. In late pregnancy, uses of NSAIDs are also associated with increased risks of premature closure of ductus arteriosus, persistent pulmonary hypertension, and a deficiency of amniotic fluid.

Migraine may occur for the first-time during pregnancy or get stronger in those who have a pre-existing migraine condition. To manage migraine attacks, paracetamol or opioids are recommended and NSAIDs should be avoided.

Cold and flu

Most common cold and flu are caused by a virus, which should resolve on its own. As such, treatment strategy is generally to relieve some symptoms, such as cough, sore throat and muscle aches.  Safe options that are available over the counter include lozenges, throat sprays and nasal sprays.

On the other hand, anti-inflammatory medications, povidone iodine, oral decongestants, senega and ammonia are not recommended during pregnancy.

Bacterial infections

Bacterial infections are treated with antibiotics, which are mostly safe to use during pregnancy with some exceptions during the first trimester. Specifically, erythromycin, metronidazole, doxycycline and trimethoprim have been associated with foetal defects and should be avoided.

Vaginal thrush

The higher oestrogen levels during pregnancy make women more likely to experience vaginal thrush. Those who have gestational diabetes are also at increased risk of developing vaginal thrush.

Usually, thrush can be treated with topical and intravaginal antifungals. These have not been associated with birth defects and are considered safe in pregnancy. For example, pessaries can be inserted into the vagina without an applicator.

A one-week course of clotrimazole is the preferred treatment as it has been shown to be more effective than nystatin. Oral fluconazole is also not recommended during pregnancy as it has been associated with an increased risk of miscarriage.


Most instances of diarrhoea during pregnancy should be short-lasting. The treatment strategy is usually to identify the cause and provide supportive therapies such as hydration salts. Loperamide or diphenoxylate may be prescribed and they are safe up to 2 doses. Note that higher doses of diphenoxylate is not suitable at or near term.

If your diarrhoea lasts for more than 2 days or you experience other symptoms such as fever or abdominal pain, please notify your doctor.

Nausea and vomiting

This is a common ailment during pregnancy, especially in the first trimester. Initial treatment strategy is typically not through medications. Instead, you may try using oral rehydration salts, avoiding triggers (food or odour), and eating smaller meals throughout the day. Ginger and vitamin B6 have also been associated with a reduction of symptoms.

However, if your symptoms are more severe and require medications, anti-emetic medications can be used, such as non-serotonin receptor antagonists.


Constipation is another common symptom during pregnancy that could be related to dietary, physical, metabolic and hormonal changes.

The first-line treatment is to implement lifestyle changes such as a fibre-rich diet (25-35g/day), plenty of water consumption (6-8 glasses/day) and regular physical exercise.

However, if these approaches are ineffective, short-term use of laxatives is the next option. Note that stimulant laxatives such as bisacodyl and senna are not recommended due to potential harm associated with high doses or prolonged use.

Heartburn and reflux

Pregnancy hormones can also affect the oesophageal sphincter, which can lead to heartburn and reflux problems. These are common throughout the pregnancy but should reduce after delivery.

Lifestyle modifications are often effective, including eating smaller meals throughout the day, avoiding late night meals and food triggers. If symptoms persist, aluminium hydroxide and ranitidine are preferred medications.

Important note

While this blog provides practical information for pregnant women, please bear in mind that you may have a specific condition that needs to be considered. When in doubt, always check with your doctor, midwife and pharmacist to see if particular medications or supplements can be used for your ailments. If you are taking any long-term medication, check with the doctor whether a safer alternative can be prescribed instead during your pregnancy.


Education Therapeutic Update, December 2019, pp. 78-85