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Side effects of medicines including vaccines

6-minute read

If you think you might be having a serious side effect, see your doctor at once. If it’s an emergency, call triple zero (000) for an ambulance.

Side effects are unwanted effects caused by medicines including vaccines. All medicines can cause side effects.

It’s important to know the side effects of your medicines so that you know what to do if you get them.

What are medicine side effects?

Any unwanted or unexpected effects of a medicine, including a vaccine, are called side effects. Side effects can also occur due to interactions with other medicines, food or alcohol.

Not all side effects are serious.

Some side effects may get better over time. For example, a new medicine might cause nausea at first but then this will go away.

Sometimes side effects don’t happen right away. They can develop after you have been taking the medicine for a while.

What is an adverse event?

Adverse events are things that happen due to the use of a medicine, vaccine, or medical device. Adverse events include side effects, but can also be caused by user error.

An adverse event does not necessarily mean that there is something wrong with the medicine, vaccine, or device.

What types of medicines can cause side effects?

All types of medicines can have side effects. This includes:

Vitamins and minerals and herbal, complementary, alternative or natural medicine can also have side effects.

Even though all medicines can cause side effects, not everyone will get them.

How can I manage the side effects?

Always take your medicine exactly according to the instructions.

Specific instructions can include:

  • starting with a low dose and increasing that dose slowly over time
  • taking your medicine with meals (for example, as recommended with anti-inflammatory medicines)
  • taking your medicine on an empty stomach (before you eat)
  • taking your medicine at a specific time of the day
  • staying out of the sun (for example, as recommended with isotretinoin)

If you are having trouble with side effects of a medicine, talk to your doctor. There may be things you can do to reduce the side effects or other medicines that suit you better.

Vaccinations and side effects

Vaccines, like other medicines, can also have side effects. However, all vaccines used in Australia offer benefits that greatly outweigh their risks.

After vaccines are given to people, their safety continues to be checked using:

  • passive surveillance
  • active surveillance

Passive surveillance requires people to report side effects to the Therapeutic Goods Administration (TGA). Find out more about reporting a side effect with a medicine.

Active surveillance is done using a system called AusVaxSafety.

AusVaxSafety sends a short text message to people after they have received a vaccination. This asks if they had a reaction to the vaccine. Experts look at the responses to make sure that any safety issues are found quickly.

You can find out more about how Australia is monitoring COVID-19 vaccine safety through the Therapeutic Goods Administration website.

Where to get information on side effects

Your doctor and pharmacist are the best people to speak to about potential side effects.

Here are some questions you might want to ask them:

  • What are the possible side effects of this medicine?
  • Does this medicine have any serious side effects?
  • How often do these side effects happen?
  • What can I do to avoid or lower my risk of side effects?
  • Do the side effects get better with time?
  • What should I do if I think I’m having a side effect?

You can also get information on side effects from the medicine’s Consumer Medicine Information (CMI) leaflet. This is given to you by the pharmacist when you are prescribed a new medicine. You can also ask your pharmacist for a copy.

All prescription medicines and some non-prescription medicines have a CMI. You can also search for CMIs in healthdirect's medicines section.

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Thinking about side effects

If you are thinking about starting a new medicine, it’s worth thinking about the side effects.

  • How common are they?
  • How serious are they?
  • And what do they mean to you?

This is especially important if you have a serious health condition, and the medicines might have serious side effects.

How to get help if you have side effects

If you think you might be having a serious side effect, see your doctor at once. If it’s an emergency, call triple zero (000) for an ambulance.

If you think you have taken too much medicine, call the Poisons Information Centre, 24 hours a day on 13 11 26.

If it’s not an emergency but the side effects are bothering you, talk to your doctor or pharmacist. You can also call healthdirect on 1800 022 222 (known as NURSE-ON-CALL in Victoria) to speak to a registered nurse.

Looking for more medicine information?

healthdirect’s medicines section allows you to search for medicines by brand name or active ingredient. It provides useful information about medicines such as:

  • their use
  • whether they are listed on the Pharmaceutical Benefits Scheme
  • product recalls

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: August 2022

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