Side effects of medicines

Side effects are unwanted effects of taking a medicine. They are also known as adverse reactions.

Not all side effects are serious, but some are. Some examples of side effects are:

• dry mouth
• rash
• nausea
• upset stomach
• bloating or constipation
• headache
• drowsiness
• soreness at injection site

When you start a new medicine ask your pharmacist about any side effects.

What is an adverse event?

An adverse event is something that results in, or could have resulted in, harm to a person. A medicine side effect is a type of adverse event.

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

If you have a side effect and have any concerns, see your doctor or pharmacist. They might need to adjust the dose or type of medicine you take.

If you think you have taken too much medicine, you can call the Poisons Information Centre (Opens in new tab), 24 hours a day on 13 11 26 for advice.

Talk to your doctor or pharmacist before stopping or changing your medicine.

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
• vaccines
• vitamins and minerals
• herbal, complementary, alternative and natural medicines

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

You can get a side effect from a medicine straight away or later.

Sometimes side effects of medicines get better over time. For example, a new medicine might make you feel nauseous at first but this will go away after you take the medicine for a while.

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

Side effects can also occur due to interactions with:

• prescription medicines
• over-the-counter medicines
• supplements
• food
• alcohol

Not all side effects can be prevented, but there are some things you can do to make them less likely.

Always take your medicine according to the instructions.

Specific instructions you might be given for a medicine include:

• starting with a low dose and increasing that dose slowly over time
• taking your medicine with meals
• taking your medicine on an empty stomach (a set time before you eat)
• taking your medicine at a specific time of the day
• staying out of the sun
• avoiding alcohol

If you don't understand the instructions, check with your pharmacist.

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.

Never take a medicine that was prescribed for someone else.

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?

Find out how to report medicine problems or side effects to the TGA (Opens in new tab).

Languages other than English

If you require information in languages other than English, Health Translations Victoria has several translated factsheets on medicines and side effects (Opens in new tab).