Packing light enough not to be charged for extra and that you will be able to port around is an art. Squeezing in a travel health kit may be the last thing on one's mind. However, in other parts of the world medications may have different names, or may even be counterfeit. Sterilization and reuse of needles is the standard of care in many parts of the world. Even for a travel itinerary with minimal risk, it is still preferable to have band aids on hand rather than having to go out and purchase them.
Some things to think about including:
Consider your health conditions. Will you be walking more than usual? In a different environment? Less control over your diet and sleep? Headaches, high blood pressure, mental disorders, allergies, asthma, are all examples of conditions that may be well controlled at home but may be a challenge to maintain on vacation. Bring the medications that you usually don't need to take.
Pack any daily medications, with extra in case of an unexpected delay.
Non-prescription medications: an anti-diarrheal, anti-nauseant, oral rehydration salts, antihistamines in case of allergies, painkillers, a cortisone cream for skin irritations, cough and cold remedies.
First aid supplies: adhesive bandages, first aid tape, hand sanitizer containing at least 60% alcohol, moleskin, vinyl gloves, gauze, tensor bandages, safety pins, scissors, thermometer, tweezers
Tropical destination? Cream or gel for sunburns, sunscreen, mosquito net, and insect repellent (containing DEET or picaridin).
A travel health kit also a great place to put backup glasses/contacts, photocopy of your passport and other important documents, an emergency contact in Canada, and address/phone of your destination.
Finally, if you have a smart phone, download Health Canada's "Travel Smart - Canada" app. It offers up to date travel advisories, contact information for Canadian embassies and consulates abroad, and a way to register with Canada's Registration of Canadians Abroad service in case of an emergency. It is a fantastic resource for the prepared traveller - Even Santa Claus uses it!