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Antibiotics are medications used to treat infections, such as otitis (ear infections), urinary tract infections, and pneumonia, when they are caused by bacteria.

They are not effective at treating infections caused by viruses, such as the common cold, flu, or COVID-19, or infections caused by fungi, such as vaginal yeast infections or fungal nail infections.

When taken correctly, they can kill bacteria or prevent them from multiplying in the human body.

There are several classes of antibiotics, the penicillins being the most well known, that treat different infections caused by different bacteria. Some antibiotics are effective against some bacteria, but ineffective against others.

Some antibiotics can be taken at home, while others—for more severe infections, for example—need to be administered at the hospital.

Antibiotics come in a variety of pharmaceutical forms, such as tablets and capsules that are swallowed, solutions that are injected into the veins, creams and ointments that are applied to the skin, and drops that are put in the eyes or ears.

Some antibiotics are also available in liquid form so that children and people who have trouble swallowing can take them more easily.

Antibiotics have many benefits if taken properly. They promote recovery and prevent complications of infection, hospitalization, and even death.


Antibiotics may cause side effects (e.g., nausea, vomiting, diarrhea, stomach ache), particularly at the start of treatment. These effects are generally tolerable and short-lived.

If you experience troublesome side effects that are persistent or severe, consult your prescribing health care provider or your pharmacist.

If you have an allergic reaction while taking antibiotics (e.g., skin rash, itching, swelling of the tongue or throat, or difficulty breathing), stop taking the medication immediately and promptly consult a health care professional or contact Info-Santé 811. It’s important to inform your prescribers and pharmacist of your allergy history.

Antibiotic resistance

Antibiotic resistance is a natural phenomenon whereby bacteria adapt and resist the antibiotic to which they were previously susceptible in order to survive. As a result, the antibiotic’s efficacy is limited, or the antibiotic becomes ineffective at treating an infection.

Antibiotic resistance is a global phenomenon that also affects Quebec. Anyone can be infected by resistant bacteria, regardless of age.

Resistant bacteria are easily spread from person to person.

They can also spread between animals. Visit the Résistance des bactéries aux antibiotiques This hyperlink will open in a new window. page (in French only) for more details.

Some bacteria are resistant to several classes of antibiotics. These are known as multidrug-resistant bacteria or superbugs.

Antibiotic resistance This hyperlink will open in a new window. can happen for several reasons:

  • Excessive or inappropriate use of antibiotics in humans and animals (e.g., prescribing an antibiotic for a viral infection or taking antibiotics in ways other than how they were prescribed)
  • Poor infection prevention and control practices (e.g., poor washing hands, failure to stay up-to-date with vaccines, unprotected sexual intercourse, improper cooking)

Antibiotic resistance leads to the following:

  • Loss of antibiotic efficacy
  • Limited choice of antibiotics
  • Difficulty treating an infection
  • Prolongation of the infection and its treatment
  • Risk of spreading the bacteria
  • Suspension of other treatments, such as cancer treatments
  • Hospitalization and suspension of work, studies, or daily activities
  • Deterioration of quality of life
  • Higher mortality
  • Medical expenses

Safe and effective use of antibiotics

Here are a few tips on how to take antibiotics safely and effectively, without harming your health:

  • Take antibiotics only when necessary and on the recommendation of a health care professional.
  • Don’t ask your health care provider for antibiotics to treat a viral infection, such as a cold or the flu. They’ll be able to recommend other treatment options to relieve your symptoms.
  • Take your antibiotics as prescribed (number and frequency of doses taken per day, duration of treatment), even if you’re feeling better or if it’s inconvenient, such as when travelling. Don’t stop your treatment or change the way you take your antibiotics on your own, without consulting your health care provider.
  • Follow the instructions provided by your pharmacist on how to store antibiotics or those indicated on the labels of over-the-counter antibiotics (e.g., creams or ointments).
  • Don’t use antibiotics prescribed for a previous infection to treat a new infection.
  • Don’t use someone else’s antibiotics or give your antibiotics to someone else.
  • Buy your antibiotics from a pharmacist.
  • Don’t take expired antibiotics. To protect the environment and reduce antibiotic resistance, expired or unused antibiotics should not be disposed of with household waste, down the sink, down the toilet, or in the municipal sewers. Return them to a pharmacy for safe disposal.

Your cooperation is essential in the fight against antibiotic resistance.

Help and resources

Health care professionals can answer your questions about the appropriate use of antibiotics, such as what health problems they can be used to treat and the consequences of misuse, including antibiotic resistance.

Your pharmacist will advise you on how best to take your antibiotics and how to store them, as well as on potential side effects and how to manage them. By following their instructions, you are helping to ensure the efficacy and safety of your treatment and contributing to the reduction of antibiotic resistance.

Last update: November 16, 2023


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