Medicines can cause unwanted side effects. All kinds of medicines, including prescription and over-the-counter medicines, herbal preparations, vitamins, and natural or herbal medicines can have side-effects. Tell your doctor about all the medicines you take, including prescription, over-the-counter and complementary medicines.
Unwanted side effects can be caused by all kinds of medicines, including prescription and over-the-counter medicines, complementary medicines including herbal preparations, vitamins, and some products dispensed by naturopaths and other practitioners of complementary medicine.
It’s estimated that around 140,000 Australians are admitted to hospital every year because of problems associated with the use of medicines, including side effects. Death can also occur in severe cases. It is in your best interests to manage your medicines wisely. See your doctor or pharmacist for further information and advice.
Prescription medicines can cause side effects
All medicines can cause unwanted side effects. For example, antibiotics such as those in the sulfonamide and penicillin families cause allergic reactions in around five per cent of the population. Skin rashes are a common reaction. However, whether a reaction is caused by the medicine or the illness that it is used to treat is sometimes difficult to tell. A further complication is the interaction of any other medicines, including complementary medicines, which the person may be taking.
Complementary medicines also cause side effects
About 60 per cent of Australians use complementary medicines at least once per year. Many people believe that alternative or complementary preparations, such as herbal remedies, are safer because they are derived from natural sources. This isn’t always true. Some herbs can act on the body as powerfully as any conventional medicine, and unwanted side effects can occur.
Examples of side effects include:
- Echinacea – more than 20 different types of reactions have been reported, including asthma attacks, hives, swelling, aching muscles and gastrointestinal upsets.
- Feverfew – pregnant women should avoid using this herb, as it can trigger uterine contractions. In animal experiments, the use of feverfew was found to trigger spontaneous abortions (miscarriages).
- Asteraceae plants – which include feverfew, echinacea, dandelion and chamomile. Side effects include allergic dermatitis and hay fever.
Complementary medicines can interact with pharmaceutical medicines
About 20 per cent of Australians are thought to take complementary medicines and pharmaceutical medicines at the same time. This increases the risk of side effects, because the active ingredients in the various preparations can ‘clash’.
Known examples of medicine interactions include the following:
- Echinacea, chamomile and milk thistle affect the liver and reduce the effectiveness of some conventional medicines or increase the risk of side effects.
- Chamomile can increase the risk of bleeding in people who are taking blood-thinning medicines such as warfarin.
- St John’s wort may reduce the effectiveness of some drugs. For example, breakthrough bleeding and unwanted pregnancy have occurred in women who take the oral contraceptive pill and St John’s wort. This herb may also reduce the effectiveness of digoxin (used for some heart problems), cyclosporin (used after organ transplants) and some other drugs.
- Using St John’s wort and a selective serotonin reuptake inhibitor (SSRI) antidepressant has been associated with serotonin syndrome, a nervous disorder caused by too much serotonin, which can range from mild to life threatening. The symptoms include confusion, agitation, restlessness, extremely high body temperature, sweating, fast heart rate, unusually increased reflexes and unusual muscle stiffness, causing poor control of movement.
Alcohol used with medicines can cause side effects
Consuming alcohol with some medicines can also cause unwanted and sometimes dangerous side effects. These effects include drowsiness with antihistamines or antidepressant medicines. This can be particularly important for drivers.
What to do if you experience side effects
- Note any side effects and consult your doctor if you have any concerns. The dose or type of medicine may need to be adjusted.
- If you are sensitive to a particular medicine, and a substitute is not available, your doctor may suggest desensitisation therapy.
- Call the NPS Medicines Line on 1300 633 424 or the Adverse Medicines Events Line on 1300 134 237 for advice. These phone-line services allow consumers to report or receive advice on side effects. They are not emergency services.
How to reduce the risk of side effects
- Take all medicines strictly as prescribed. Taking medication incorrectly can cause side effects.
- Don’t take anyone else’s medicines.
- Learn about your medication. All prescription medicines have an information leaflet called Consumer Medicine Information (CMI). This includes detailed information on the medicine in plain English, including use, side effects and precautions. Your pharmacist can give you the CMI for your medicine.
- Ask your pharmacist for advice if you buy over-the-counter medicines. They can advise you about side effects and interactions with other medicines you are taking. You should be aware that medicines you buy in the supermarket can also cause side effects.
- Tell your doctor about all the medicines you take, including prescription, over-the-counter and complementary medicines.
- Ask your doctor if improving your lifestyle could reduce your need for medication. Some conditions can be better managed with changes to your diet and regular exercise.
- Have an annual review of all the medicines you take. For the elderly, this is essential because, as we age, we are more likely to have side effects from medicines. Any medicines considered no longer necessary should be stopped. Ask your doctor if you might benefit from a Home Medicines Review. A pharmacist will review all the medicines you take. One reason to do this is to prevent medicine-related problems.
- Return unwanted and out-of-date medicines to your pharmacy for environmentally safe disposal. This service is provided free of charge.
- Talk to your pharmacist about dosage aids that can help you organise your pill taking. You may be at risk of making mistakes if you take many different medicines at different times.
- Ask your doctor or pharmacist questions, so you can clearly understand the benefits and risks of your medicines.
Where to get help
- Your doctor
- NURSE-ON-CALL Tel. 1300 60 60 24 – for expert health information and advice (24 hours, 7 days)
- Your pharmacist
- Adverse Medicines Events (AME) Line Tel. 1300 134 237 – to report a problem with your medicine
- Medicines Line Tel. 1300 MEDICINE (1300 633 424) – for information on prescription, over-the-counter and complementary medicines
- Victorian Poisons Information Centre Tel. 13 11 26 – seven days a week, 24 hours a day – for advice about poisonings, suspected poisonings, bites and stings, mistakes with medicines and poisoning prevention advice.
- In an emergency, always call triple zero (000)
Things to remember
- Unwanted side effects can be caused by all kinds of medicines, including prescription and over-the-counter medicines, and complementary medicines such as herbal preparations and vitamins.
- If you are worried about any medicines you are taking, you should seek immediate medical attention.
- Taking some complementary medicines and prescription medicines at the same time can increase the risk of side effects, because the active ingredients in the various preparations can ‘clash’.
- Tell your doctor about all the medicines you are taking, including prescription, over-the-counter and complementary. You may like to have an annual review of all your medications.
You might also be interested in:
- Complementary medicines - tell your doctor.
- Medications - non-steroidal anti-inflammatory drugs.
- Medicines - safety issues.
- Pain management - adults.
- Pain management - children.
- Prescription medicines.
Want to know more?
Go to More information for support groups, related links and references.
This page has been produced in consultation with and approved by:
(Logo links to further information)
Fact sheet currently being reviewed.
Last reviewed: June 2012
Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your doctor or other registered health professional. Content has been prepared for Victorian residents and wider Australian audiences, and was accurate at the time of publication. Readers should note that, over time, currency and completeness of the information may change. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions.
Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your qualified health professional. Content has been prepared for Victorian residence and wider Australian audiences, and was accurate at the time of publication. Readers should note that over time currency and completeness of the information may change. All users are urged to always seek advice from a qualified health care professional for diagnosis and answers to their medical questions.
For the latest updates and more information, visit www.betterhealth.vic.gov.au
Copyight © 1999/2015 State of Victoria. Reproduced from the Better Health Channel (www.betterhealth.vic.gov.au) at no cost with permission of the Victorian Minister for Health. Unauthorised reproduction and other uses comprised in the copyright are prohibited without permission.