Published on April 12, 2024 at 8:00 / Updated on May 1, 2024 at 8:00

The role of antibiotics

Antibiotics are drugs that kill bacteria or prevent them from reproducing. They are commonly used to cure diseases caused by bacteria, such as otitis, tuberculosis, and pneumonia. They are also sometimes prescribed to prevent complications from an infection. Antibiotics, when used properly, save many lives every day.

However, they are ineffective against illnesses caused by viruses, such as the common cold and the flu. They will not cure or improve symptoms of viral infections. It can sometimes be difficult to differentiate a bacterial infection from a viral infection. It is therefore important to consult your health care provider to make sure you get the right treatment.

Efficacy of antibiotics

Antibiotics are effective when used under certain conditions.

The right antibiotic must be used to treat a specific infection. Some medications that are highly effective for a tooth infection, for example, will not help with a sinus infection. In addition, an infection may be caused by a single bacteria or many. Sometimes, tests are needed to find the bacteria that caused the infection.

Antibiotics must be taken as directed. It is very important to follow the instructions from your pharmacist.

Antibiotic Resistance

Antibiotic resistance happens when the antibiotics normally used to treat a specific type of bacteria do not work as well or fail completely. As bacteria are living organisms capable of adapting, they can develop defences against the antibiotic.

When this happens, a different drug must be used to kill the bacteria. Unfortunately, antibiotic resistance is an increasingly common problem. One day, we may no longer have effective antibiotics for certain bacteria.


Antibiotic allergies can be serious and should not be taken lightly. Always tell your health care provider(s) about any antibiotic allergies you have and the reaction that has occurred. Consult a health care professional immediately if you experience any of the following symptoms after taking an antibiotic:

  • Red patches of skin
  • Itching
  • Swelling
  • Difficulty breathing

If an allergy is confirmed, a different antibiotic may be prescribed. Note that some people may experience adverse effects, which are not the same as an allergy.

Adverse Effects of Antibiotics

Our bodies need certain microorganisms to work properly. They make up our normal flora and protect us from other microbes that can make us sick (pathogens). Antibiotic use can disrupt our normal flora, leading to a secondary infection by a pathogen.

Here are two examples of adverse effects due to an imbalance in normal flora caused by an antibiotic:


  • Your pharmacist may recommend that you take probiotics during treatment to prevent diarrhea. However, some people carry a bacteria called Clostridioides difficile in their intestines. This bacteria is usually harmless to humans, but when allowed to multiply freely, it can become harmful, especially to the elderly. Seek medical attention if you experience any of the following symptoms, even several days after stopping an antibiotic:
    • Liquid diarrhea (three or more bowel movements per day for at least two days)
    • Fever
    • Abdominal pain
    • Loss of appetite
    • Dehydration
    • Nausea

Yeast infections

  • For many women, antibiotics can imbalance the normal flora of the vagina or vulva, resulting in a yeast infection (candidiasis). Your pharmacist can advise you on the appropriate treatment.

Drug Interactions

Antibiotics can interact with other drugs. This is why it is important to tell your pharmacist if you're taking any medications, natural health products, multivitamins, or minerals.

Antibiotics in Children

Here are some important things to keep in mind to ensure appropriate antibiotic use in children:

The child's weight

  • You will need to know the child's body weight, so that the right dose of medication is given. If the dose is too low, it may be ineffective. If the dose is too high, the risk of adverse effects goes up unnecessarily.

Dose accuracy

  • Be sure to accurately measure the dose so that the treatment is effective. For liquids, always use the dosing tool provided by your pharmacist.
  • Shake liquid antibiotics well before administering them. The drug tends to settle to the bottom and the measured dose would not have the right amount of medication.


  • Store liquid antibiotics at the recommended temperature.

Form and flavour preferences

  • Mention your child's preferences at the pharmacy. If possible, your pharmacist will choose the form and flavour that your child will like best.

Duration of treatment

  • Complete the full course of antibiotics prescribed by your health care provider. If there is any medication left after this time, it is important to discard it. It should not be used after the expiration date on the bottle.
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