What is a medicine?
A medicine is a substance used to treat illness, prevent disease, or relieve symptoms like pain and fever. People have used medicines for thousands of years. Willow bark was chewed for pain by ancient Egyptians and Greeks; it contains a chemical related to aspirin.
Today most medicines are pharmaceutical drugs, made by drug companies and tested carefully for safety.
Types of medicines
| Type | What it does | Example |
|---|---|---|
| Pain relievers | Reduce pain, fever or swelling | Acetaminophen, ibuprofen |
| Antibiotics | Kill bacteria | Amoxicillin |
| Antivirals | Slow viruses | Treatments for flu and HIV |
| Vaccines | Train the immune system to prevent disease | Measles vaccine |
| Antihistamines | Reduce allergy symptoms | Allergy pills |
| Insulin | Controls blood sugar | For people with diabetes |
| Inhalers | Open airways | For asthma |
Prescription and over-the-counter
| Prescription medicine | Over-the-counter medicine |
|---|---|
| A doctor or nurse practitioner must order it | Can be bought at a pharmacy or store |
| Usually stronger or needs monitoring | Usually for minor problems |
| Antibiotics, insulin | Cough syrup, pain relievers |
Pharmacists are experts on medicines. They can answer questions about how to take a medicine and whether it’s safe with other medicines.
How medicines get into the body
- By mouth: pills, liquids, chewables (absorbed through the stomach and intestines)
- Injection: into a muscle, under the skin or into a vein (works quickly)
- Inhaled: through the lungs (asthma inhalers)
- On the skin: creams, patches
- Drops: eyes, ears or nose
Dose matters
The dose is how much medicine to take and how often. Too little might not work; too much can be dangerous. The right dose can depend on age, weight, and health. Children’s doses are often different from adults’, so always follow the label or a doctor’s instructions.
Side effects
A side effect is an unwanted effect. Common ones include an upset stomach, sleepiness or a rash. Most are mild, but some can be serious. Some people have allergic reactions to certain medicines. Mixing medicines can also cause problems, which is why doctors and pharmacists ask what else you take.
How a new medicine is developed
Making a new medicine often takes 10–15 years and costs hundreds of millions to billions of dollars.
| Stage | What happens |
|---|---|
| Discovery | Scientists find a chemical that might work, often by testing thousands |
| Lab and animal testing | Checks whether it works and is safe enough to try in people |
| Clinical trial Phase 1 | Small group of healthy volunteers; checks safety and dose |
| Phase 2 | Hundreds of patients; checks whether it works |
| Phase 3 | Thousands of patients; compares with existing treatments or a placebo |
| Approval | A government agency reviews all the evidence (Health Canada in Canada, the FDA in the U.S.) |
| Monitoring | Doctors keep reporting side effects after approval |
A placebo is a fake treatment, like a sugar pill. Comparing a real medicine with a placebo shows whether the medicine truly works.
Milestones in medicine
| Year | Discovery |
|---|---|
| 1796 | Edward Jenner’s smallpox vaccine |
| 1897 | Aspirin made in a lab |
| 1921–22 | Insulin discovered by Frederick Banting, Charles Best, J. J. R. Macleod and James Collip in Toronto |
| 1928 | Penicillin discovered by Alexander Fleming |
| 1955 | Polio vaccine by Jonas Salk |
| 2020 | First mRNA vaccines approved, for COVID-19 |
Before insulin, type 1 diabetes was almost always fatal. Banting and Macleod won the 1923 Nobel Prize, and they shared it with Best and Collip.
Using medicines safely
- Take medicine only with a trusted adult’s help.
- Follow the label or the doctor’s instructions exactly.
- Never take someone else’s prescription.
- Keep medicines locked away from young children.
- Return old medicines to a pharmacy for safe disposal.
- Finish antibiotics as prescribed.
Common mistakes
- Thinking more medicine works better. Extra doses can be harmful.
- Thinking "natural" always means safe. Herbal products can have side effects and interactions.
- Thinking antibiotics treat every illness. They work only on bacteria.
Try it yourself
- Look at the label on an over-the-counter medicine box (with an adult). Find the medicinal ingredient, the dose and the warnings.
- Design a fair clinical trial for a new headache pill. What will the control group get?
- Research a medicine discovered in Canada and present how it changed people’s lives.
Quick recap
- Medicines treat, prevent or relieve illness.
- Some need a prescription; others are sold over the counter.
- The right dose matters, and all medicines can have side effects.
- New medicines go through years of testing, including clinical trials.
- Use medicines safely and only as directed.