Medication mistakes are more common than most Canadians realize — and some of them can be deadly. Whether you pick up a prescription at your local pharmacy or grab something off the shelf at the drug store, how you take your medication matters just as much as what you take. In this article, we walk through six of the most dangerous errors people make with medications, and how you can avoid them.
Why Medication Mistakes Happen
Medications only work the way they should when they are used correctly. Unfortunately, errors happen all the time — in hospitals, pharmacies, and at home. Sometimes a doctor’s handwriting is hard to read. Other times, a patient simply forgets the instructions or assumes a drug is harmless because it doesn’t need a prescription.
According to Health Canada’s MedEffect program, thousands of adverse drug reactions are reported in Canada each year. Many of these are preventable. Understanding the most common medication mistakes is the first step toward keeping yourself and your family safe.
Medication Mistake #1: Taking the Wrong Dose
Dosage errors are one of the most serious medication mistakes a person can make. A single misplaced decimal point can turn a safe dose into a dangerous one. For example, there is a 1,000-fold difference between one microgram (mcg) and one milligram (mg) — and that kind of error can be fatal.
Every time you pick up a prescription, take a moment to read the label carefully. Make sure the dose your pharmacist gives you matches what your doctor prescribed. If anything looks different or confusing, ask your pharmacist to explain it before you leave the counter.
For liquid medications, always use the measuring device that comes with the product. A regular kitchen teaspoon is not accurate enough for medication. Using a proper dosing syringe or cup helps prevent over- or under-dosing.
Medication Mistake #2: Mixing Up Similar Drug Names
Many medications have names that sound or look almost identical, even though they treat very different conditions. This is a surprisingly common source of medication mistakes at pharmacies across Canada.
For example, Paxil (an antidepressant) and Plavix (a blood thinner) look similar on paper — especially if a doctor’s handwriting is hard to read. Receiving the wrong drug could have serious health consequences, depending on your condition.
To protect yourself, always double-check your medication when you get home. Confirm the drug name, the dose, and what it is supposed to treat. If something doesn’t match what your doctor told you, call your pharmacy right away. Your pharmacist is a valuable resource and is happy to help.
Tips to Avoid Name Confusion
Ask your doctor to print the drug name clearly, or request an electronic prescription.
Look up the medication name online before leaving the pharmacy.
Keep a personal medication list and compare it each time you pick up a refill.
Medication Mistake #3: Accidentally Doubling Up on Similar Drugs
If you take medication for more than one health condition, it is easy to accidentally take two drugs that do the same thing. This is one of the most dangerous medication mistakes, because combining similar drugs can push your body past its limit.
Consider someone who takes one medication for anxiety, another for pain, and a third to help with sleep. All three of these may be sedatives — meaning they slow down your nervous system. Taking them together can cause your breathing to slow dangerously, or even stop.
This risk applies to prescription drugs and over-the-counter products alike. For instance, combining an antihistamine (found in many cold and allergy products), a cough suppressant, and a sleep aid can be toxic — even if you bought all three at your local pharmacy without a prescription.
As a general rule: if a drug’s label warns that drowsiness is a side effect, do not combine it with any other sedative — including alcohol. Always review all your medications with your family doctor or pharmacist to check for overlap.
Medication Mistake #4: Mixing Medication with Alcohol
Combining alcohol with medication is a common but very risky habit. Many Canadians do not realize how dangerous this combination can be — even with drugs you can buy without a prescription.
Alcohol can interact with a wide range of medications, including pain relievers, antihistamines, antidepressants, and sleeping pills. These interactions can damage your liver, slow your heart rate, or raise your blood pressure to dangerous levels. In serious cases, the combination can be life-threatening.
For example, drinking alcohol while taking antidepressants can cause a sudden spike in blood pressure. Mixing alcohol with sleeping pills can slow your heart rate and breathing to dangerous levels. Even common cold and flu remedies — like NyQuil-style products — can cause toxic reactions when mixed with alcohol.
According to the Mayo Clinic’s guide on alcohol and medications, even small amounts of alcohol can interfere with how your body processes certain drugs. If you are unsure whether your medication is safe to take with alcohol, ask your pharmacist — it takes less than a minute and could save your life.
Common Drug and Alcohol Combinations to Avoid
Antidepressants + alcohol: Risk of high blood pressure and worsened depression.
Sleeping pills + alcohol: Risk of dangerously slow heart rate and breathing.
Pain relievers (like acetaminophen) + alcohol: Serious risk of liver damage.
Cold and flu medication + alcohol: Risk of toxic reaction and extreme drowsiness.
Medication Mistake #5: Combining Prescription Drugs with Over-the-Counter Products
Just because you can buy something without a prescription does not mean it is harmless. Over-the-counter (OTC) drugs are simply lower-potency versions of the same types of medication your doctor prescribes. They still carry real risks — especially when mixed with prescription drugs.
Natural health products and supplements also fall into this category. For example, St. John’s Wort is a popular herbal remedy that some people use for low mood. However, it is also a mild antidepressant — and taking it alongside a prescription antidepressant can lead to a dangerous condition called serotonin syndrome.
Even something as familiar as aspirin can cause problems. Aspirin can interfere with prescription blood thinners like warfarin or digoxin, increasing the risk of serious bleeding. It can also interact with medications used to treat heart conditions.
Always tell your family doctor and pharmacist about every product you take — including vitamins, supplements, and herbal remedies. This information helps them spot dangerous combinations before they become a problem. Many provincial health plans cover medication review appointments with your pharmacist, so take advantage of that service.
Medication Mistake #6: Ignoring the Drug Information Leaflet
Every medication — whether prescription or over-the-counter — comes with a drug information leaflet. Most people toss it in the recycling bin without a second glance. That is a mistake.
The leaflet tells you how to take the drug correctly, what side effects to watch for, and which other medications or foods to avoid. Ignoring this information is one of the easiest medication mistakes to make — and one of the easiest to fix.
For example, over-the-counter pain relievers like ibuprofen and aspirin can cause gastrointestinal bleeding if taken incorrectly or in doses that are too high. Antacids can reduce the effectiveness of other medications if taken at the wrong time. These are details you will only know if you read the label.
Take five minutes to read the information leaflet when you start a new medication. If you have questions, your pharmacist can walk you through anything that is unclear. That is exactly what they are there for.
When to See a Doctor or Pharmacist
If you think you have made a medication mistake — or if you feel unwell after taking a drug — do not wait. Contact your family doctor, visit a walk-in clinic, or call your provincial health line right away. In Canada, most provinces offer a free nurse advice line (such as Health811 in Ontario or 811 in British Columbia and Alberta) available 24 hours a day.
If you are experiencing a severe reaction — such as difficulty breathing, chest pain, or loss of consciousness — call 911 immediately or go to your nearest emergency department.
It is also a good idea to schedule a routine medication review with your family doctor or pharmacist, especially if you take more than one medication regularly. Many provincial health plans cover this service. A pharmacist can catch dangerous interactions you might not even know to look for.
Remember: no question about your medications is too small. Your health team is there to help you stay safe. Always speak with a qualified healthcare provider before making any changes to your medications or starting something new.
Frequently Asked Questions About Medication Mistakes
What are the most common medication mistakes people make at home?
The most common medication mistakes at home include taking the wrong dose, mixing prescription drugs with over-the-counter products, and combining medications with alcohol. Skipping doses or stopping a medication early are also very frequent errors. Always follow your doctor’s or pharmacist’s instructions carefully.
Can over-the-counter drugs cause dangerous drug interactions?
Yes — over-the-counter drugs can absolutely cause dangerous interactions, and this is one of the most overlooked medication mistakes. Products like antihistamines, pain relievers, and herbal supplements can interact with prescription medications in harmful ways. Always tell your pharmacist about every product you take, including vitamins and natural health products.
Is it safe to drink alcohol while taking prescription medication?
In most cases, mixing alcohol with prescription medication is not safe and is one of the more serious medication mistakes you can make. Alcohol can intensify the effects of sedatives, damage your liver when combined with pain relievers, and dangerously raise or lower your blood pressure when mixed with antidepressants. Check with your pharmacist before drinking alcohol if you are on any regular medication.
How can I avoid getting the wrong medication at the pharmacy?
To avoid this type of medication mistake, always check your prescription bag before leaving the pharmacy. Confirm the drug name, dose, and intended use match what your doctor told you. Asking your doctor to send prescriptions electronically also reduces the risk of errors caused by hard-to-read handwriting.
What should I do if I think I made a medication mistake?
If you think you have made a medication mistake, contact your family doctor, visit a walk-in clinic, or call your provincial health advice line (such as 811) right away. For severe symptoms like difficulty breathing or chest pain, call 911 immediately. Healthline’s guide on medication errors also offers helpful information on next steps.
Does Health Canada track medication errors and drug reactions?
Yes. Health Canada’s MedEffect program collects reports of adverse drug reactions from both healthcare providers and the public. Reporting a medication mistake or unexpected reaction helps Health Canada monitor drug safety across the country. You can submit a report directly through the Health Canada website.
Key Takeaways
Check your dose every time. Even a small error in dosage can have serious consequences. Read your label carefully and use proper measuring tools for liquid medications.
Watch out for look-alike drug names. Always verify the name and purpose of your medication when you pick up a prescription.
Avoid doubling up on similar drugs. If more than one of your medications causes drowsiness, talk to your doctor or pharmacist about the combined effect.
Never mix medication with alcohol without checking first. Many common drugs — both prescription and OTC — can cause dangerous reactions with alcohol.
Tell your health team everything you take. That includes vitamins, supplements, and herbal products. There is no such thing as “too harmless to mention.”
Read the information leaflet. It takes only a few minutes and can help you avoid preventable medication mistakes.
When in doubt, ask. Your pharmacist, family doctor, or walk-in clinic are all excellent resources. Many provincial health plans also cover medication review services at no extra cost to you.
