Influenza (Flu)

Last Update: 31 Mar 2025

Condition

Table of content

1. What is it? 2. Why treating? 3. Non-Medical Options 4. Medications 5. Breastfeeding/ chestfeeding 6. Key Takeaways 7. Limits of Research

Welcome to our Fact Sheet on influenza commonly known as the flu, during pregnancy. The information is based on current research and may be updated as new scientific knowledge emerges. It’s important to remember that the content shared here does not replace personalized advice from healthcare professionals.

1. What is influenza and how can I recognize the symptoms?

Influenza, known as the flu, is a common contagious viral infection, especially during the falls and winter months. It affects the respiratory system, including your nose, throat, and lungs.

The virus spreads easily from person to person, usually through droplets when someone with the flu coughs, sneezes, or talks. You can also catch it by touching contaminated surfaces and then touching your face. On surfaces like doorknobs or counters, the virus can remain infectious for up to 48 hours.

The flu’s incubation period—known as the number of days it takes from time you are first exposed to the virus until the appearance of the first symptoms—can range from 1 to 4 days. Adults are most contagious during the first 3 to 4 days of illness, while children can spread the virus for longer.

There are two main types of flu viruses: Influenza A and Influenza B. These viruses change slightly each year, which is why the flu vaccine is updated annually to match the most common strains.

The flu can feel like a cold, but its symptoms typically appear much more suddenly and severely, a bit like COVID-19. A test can be done to determine which infection it is. Here are some of the symptoms you may experience:

Symptoms of Influenza:

Sudden fever 38-41℃ (100.4-104 F)
Headache
Muscle or joint pain
Sore throat
Cough
Runny or stuffy nose
Extreme fatigue
Nausea, vomiting, or diarrhea (more common in children)

If you experience any of these symptoms, especially during pregnancy, it’s important to rest, stay hydrated, and consult your healthcare provider. Pregnant persons and those who have recently given birth (within 4 weeks postpartum) are at higher risk for flu-related complications. Taking preventive measures and addressing symptoms early can help keep you and your baby safe.

2. Why is it important to treat influenza during pregnancy?

During pregnancy, your body goes through many changes, including a natural weakening of the immune system, which can make you more vulnerable to illnesses like the flu. Monitoring and treating the flu is important because if left untreated, it can lead to serious complications that could affect both you and your baby, such as pneumonia, breathing difficulties, hospitalization, or even early labor.

Understanding Risks in Pregnancy

Research helps us estimate the risks linked to common pregnancy-related conditions. Miscarriages, congenital malformations tooltip, premature birth, and other complications can happen in any pregnancy for many reasons. These are called background risks. Here we compare this background risk with the risks associated with the untreated condition.

So far, no link has been found between influenza and pregnancy outcomes such as malformations or long-term health problems. However, some research have found a potential increased chance to give birth early and have a low birth weight baby. By addressing flu symptoms early, you can reduce these risks, recover faster, and protect your baby from any potential harm. Taking care of yourself means taking care of your little one too.

Table 1 below provides a summary of the potential impacts of untreated influenza during pregnancy compared to the background risks. Keep in mind that these risks can be influenced by factors like the pregnant person’s age, genetics, ethnicity, lifestyle, and other medical conditions.

Table 1: Potential impacts of untreated influenza during pregnancy.

For who?	What?	What does research say?
For the pregnant person	Pneumonia	Pregnant women with influenza are 10 times more likely to develop pneumonia compared to the general population (12% vs. <1%).
	Hospitalisation	Risk of hospitalization increases, especially in the 3rd trimester, with added risks if you have conditions like diabetes or anemia.
	Miscarriage	Some studies suggest an increased risk, but more research is needed.
For the unborn child	Premature birth	Some studies found a slightly increased risk of preterm birth (before 37 weeks).
	Growth	Some studies show a small chance of low birth weight (5 pounds and 8 ounces or 2,500 g).
	Congenital malformations	Having the flu during pregnancy has not been proven to cause birth defects. But a high fever from the flu in early pregnancy may slightly raise the risk of birth defects.
For future child/adult	Brain development	No evidence of long-term mental risks like dementia.

It’s also important to remember that the flu can be passed to your newborn, so preventing the flu during pregnancy helps protect your baby, especially in those early months when they are most vulnerable.

Preventive measures, such as getting the flu vaccine and seeking medical care if symptoms arise, helps lower the risks for both you and your baby. When you get the flu shot during pregnancy, you pass on valuable protection to your baby, which is important since babies under 6 months are too young to be vaccinated. This protects your baby during the time they are most vulnerable to flu-related complications.

3. What Can I Do to Manage my Influenza Before Medications?

If you’re experiencing flu symptoms, there are several steps you can take to manage your infection before starting any medications:

Rest: Allow your body to recover by getting plenty of rest.
Stay hydrated: Drink water, clear broths, or herbal teas to avoid dehydration.
Use a humidifier: Adding moisture to the air can ease congestion and soothe your throat.
Gargle with salt water: This can help relieve a sore throat.
Elevate your head: Sleeping with an extra pillow can help relieve a stuffy nose and improve breathing.
Stay isolated: Avoid close contact with others, especially your baby, to prevent spreading the flu.
Practice good hygiene: Wash your hands regularly and wear a mask to reduce transmission risks.

These steps can help manage your symptoms and support your recovery until you consult your healthcare provider for further guidance.

4. Medications Prescribed for Treating Influenza

If non-medical treatments aren’t enough to relieve your flu symptoms, your healthcare provider may recommend medications. Some over-the-counter options can help manage symptoms, and in certain cases, prescription antivirals may be necessary to treat the flu. In Canada, antiviral drugs are most effective when started within 48 hours of the first symptoms.

Over-the-counter (without prescription) medications can help relieve symptoms like fever, congestion, and body aches:

Acetaminophen (e.g., Tylenol®): Commonly used to reduce fever and relieve pain. Generally recommended during pregnancy.

Ibuprofen (e.g., Advil®, Motrin®): A non-steroidal anti-inflammatory drug (NSAID) that can help with pain relief, but always consult your healthcare provider before use, especially after 20 weeks of gestation.

Decongestants (e.g., Otrivin®, Drixoral®): Help relieve nasal congestion, but some contain ingredients that may not be suitable during pregnancy. Always consult your pharmacist to find the best option for you.

Cough syrups (e.g., Benylin-DM®, Robitussin®): May help soothe a cough. Always consult your pharmacist to find the best option for you.

In some cases, an antiviral to treat the infection can be prescribed by your doctor to treat influenza:

Oseltamivir (e.g., Tamiflu®): This is the most prescribed antiviral for the flu. It has been studied extensively and is generally considered a good option for most people, including pregnant persons.

Zanamivir (e.g., Relenza®): Another option for treating flu, often used when oseltamivir isn’t suitable.

Amantadine (e.g., Symmetrel®): Used specifically for Influenza A but less frequently prescribed due to high levels of resistance, meaning it doesn’t always work well against the virus.

To know more about a specific medication, please consult the associated Fact Sheet and always discuss with your healthcare provider before making changes to your medication intake during pregnancy.

Table 2. Some medications available in Canada to treat influenza.

Medication Types	Medication Names	Brand names
Antivirals	Oseltamivir	e.g. Tamiflu®
	Zanamivir	e.g. Relenza®
	Amantadine	e.g. Symmetrel®
Pain relief	Acetaminophen, paracetamol	e.g. Tylenol®
Non-steroidal anti-inflammatory drugs (NSAIDs)	Ibuprofen	e.g. Advil®, Motrin®
Non-steroidal anti-inflammatory drugs (NSAIDs)	Naproxen	e.g. Aleve®, Naprosyn®, Anaprox®
Cough Suppressants	Dextromethorphan	e.g. Benylin-DM®, Robitussin®
codeine	–
Antihistamines	Chlorpheniramine	e.g. Chlor-Triplon®
	Diphenhydramine	e.g. Benadryl®
	Pseudoephedrine	e.g. Sudafed®
	Hydroxyzine	e.g. Atarax®
Nasal Decongestants	Oxymetazoline	e.g. Claritin®, Dristan®
Nasal Decongestants	Saline Solution	e.g. HydraSense®, Salinex®, SinusRinse®

How do I know which one to take?

Each medication has its benefits and potential risks, which is why it’s important to work with your healthcare team—including your pharmacist, nurse, doctor, or midwife—to make the best decision for you and your baby. They will help you weigh the options based on your unique situation. Your healthcare provider will consider your symptoms, the stage of your pregnancy, and any other health conditions when helping you choose the right treatment.

For treating influenza during pregnancy, the common recommendation is oseltamivir (Tamiflu®) as the best antiviral, especially in late pregnancy. Oseltamivir is taken as a pill and works throughout your body to fight the virus. Another antiviral, zanamivir (Relenza®), is inhaled, but it may not work as well during pregnancy. As the baby grows, your uterus can press on your lungs, making it harder for inhaled medications to spread evenly.

In addition to antivirals, your healthcare team may suggest over-the-counter (not prescribed) medications like acetaminophen (Tylenol®) to manage fever and body aches. Be sure to ask your pharmacist or doctor before using any over-the-counter decongestants, cough syrups, or pain relievers to make sure they’re safe for you during pregnancy.

The most important step is to talk to your healthcare provider before starting any medication, so you can feel confident that you’re making the safest choice for both you and your baby.

5. Will I Be Able to Breastfeed/ chestfeed?

Breastfeeding is still possible while you have the infection. The influenza virus does not pass through breast milk, so it’s safe for your baby. In fact, breast milk provides important antibodies that help protect your newborn’s health.

To reduce the risk of spreading the flu to your baby, it’s recommended to:

Wash your hands thoroughly before feeding
Wear a mask while breastfeeding or handling your baby

By following these simple precautions, you can keep breastfeeding while keeping your baby safe.

If you choose to breastfeed and have questions, don’t hesitate to seek help from your healthcare professional (doctor, nurse, pharmacist) or a lactation consultant.

Key Takeaways

Influenza is a contagious virus that affects the respiratory system, spreading through droplets, direct contact, or surfaces.
Treating influenza during pregnancy is important to prevent complications such as pneumonia, preterm labor, and hospitalization.
Rest, hydration, and proper hygiene are key non-medication ways to manage flu symptoms before seeking medical treatment.
Antivirals like oseltamivir (Tamiflu®) and zanamivir (Relenza®) may be prescribed during pregnancy, but always consult your healthcare team before taking medications.
The flu virus is not transmitted through breast milk, so you can continue breastfeeding with precautions like hand washing and wearing a mask.
The flu vaccine is strongly recommended during pregnancy to protect both you and your baby from severe illness.

Research Is Great, But It Is Not Perfect

Making informed health decisions also involves considering the current state of scientific knowledge. Here are some considerations, found by our team, on the quantity and qualities of studies available so far on influenza during pregnancy:

Other factors: The presence of confounding factors, such as other medications taken during pregnancy, can influence study results.

Associated illness: Difficulty in distinguishing the effects of influenza from other associated illnesses may lead to overestimating its impact on pregnancy.

Self-reported symptoms: Many studies rely on self-reported data, which can introduce bias and make it harder to accurately measure the severity of influenza and its complications during pregnancy.

Varying definitions of influenza: Some studies define influenza based on clinical symptoms rather than laboratory-confirmed cases, which can lead to misclassification and affect the accuracy of findings.

These factors can affect the accuracy and reliability of current research, which is why it’s important to consult your healthcare team for personalized advice.

For more information, you can also consult the following resources:

https://immunize.ca/influenza

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