Side effects of medicines including vaccines

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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:

prescription medicines
over-the-counter medicines that you can buy from a pharmacy, supermarket or other shops

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 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.
COVID-19 vaccination side effects
Vaccination against COVID-19 is the best way to reduce deaths and severe illness. The protective benefits of vaccination far outweigh the potential risks.
Like all medicines, COVID-19 vaccines may cause some side effects. The most frequently reported side effects are:

Myocarditis (inflammation of the heart) is a known but very rare side effect of the Comirnaty (Pfizer) and Spikevax (Moderna) COVID-19 vaccines. Most people get better within a few days. Myocarditis is reported in:

However, it is more common after the second dose in 12 to 17 year-old boys and in men under 30 years.
Thrombosis with thrombocytopenia syndrome (TTS) is a very rare but serious side effect of the Vaxzevria (AstraZeneca) COVID-19 vaccine. TTS is reported in:

about 2 in every 100,000 people who get Vaxzevria (AstraZeneca), following their first dose

The risk of TTS is much lower after the second dose of this vaccine.
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:

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

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.