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Dealing With Medicine Side Effects and Interactions


All medicines can cause side effects. Many people don't have side effects. And minor side effects sometimes go away after a while.

But sometimes side effects can be a problem or can be serious.

If you're having problems with side effects, talk to your doctor. Your doctor may be able to lower your dose or change to a different medicine.

Always be sure you get specific information on the medicine you're taking. For a full list of side effects, check the information that came with the medicine you're using. If you have questions, talk to your pharmacist or doctor.

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Side Effects

Anyone can feel side effects from a medicine. There is no way to know for sure if a medicine will cause side effects for you. It may depend on how much of the medicine you take, how old you are, and how much you weigh. It also may depend on your sex and what other health problems you have. Older adults are more likely to have side effects than younger adults.

You may notice side effects when you start to take a medicine, change the dose, or stop using the medicine. And a medicine you've often taken without getting side effects may suddenly cause side effects. Or the side effects may stop.

Here are some important things to think about when taking medicines:

  • Usually the benefits of the medicine are more important than minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects continue to bother you and you wonder if you should keep taking the medicine, call your doctor. Your doctor may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

When to call

Call 911 or other emergency services right away if you take a medicine and you:

  • Have trouble breathing.
  • Get hives.
  • Have swelling of your face, lips, tongue, or throat.
  • Faint (lose consciousness) or feel like you may faint.

Preventing side effects

There are many things you can do to prevent and prepare for side effects. Before you take any medicine, talk to your doctor or pharmacist about:

  • The possible side effects of the medicine and those you may be likely to have.
  • How soon side effects may start.
  • Whether they may go away on their own.
  • Whether you can do anything to prevent them. For example, taking a medicine with food or at a certain time of day may help with side effects.
  • Whether you need any tests to check for side effects.
  • What you can do to manage mild side effects.
  • When and who you should call for help with side effects.
  • Whether you can drink alcohol when you are taking the medicine.

Dealing with mild side effects

Medicines work in a delicate balance with your body and with each other. Sometimes the balance tips, and this can cause side effects or medicine interactions.

Do not suddenly quit taking your medicine. Always talk to your doctor first. Suddenly stopping could cause your symptoms to come back or could cause other health problems.

Here are some tips to help you manage some common side effects from medicines.

  • Eat bran and other whole grain cereals and high-fibre fruits and vegetables, such as apples, prunes, beans, and broccoli.
  • Drink plenty of fluids.
  • Get exercise.
Daytime drowsiness.
  • This problem usually goes away as your body adjusts to the medicine.
  • Ask your doctor if you can take your medicine at bedtime.
  • Do not drive or operate heavy equipment when you feel drowsy.
  • Eat mild, low-fibre foods, such as applesauce, rice, and yogurt.
  • Avoid spicy and high-fat foods until you feel better.
  • Get up slowly from sitting or lying down.
Dry mouth.
  • Chew sugarless gum or suck on sugarless candy.
  • Take frequent sips of water throughout the day.
  • These usually will go away as your body adjusts to the medicine.
  • Ask your doctor what medicine you can take for a headache.
Loss of appetite.
  • Try to eat more often. Have healthy snacks between meals.
  • Include favourite foods at each meal.
  • Take a walk before you eat. This may make you more hungry.
  • Eat several smaller meals a day rather than two or three large meals.
  • Try peppermint candy or gum. Peppermint can help settle your stomach.
  • Eat bland foods, such as dry crackers or plain bread. Avoid fried, greasy, sweet, and spicy foods.
  • Ask your doctor if you can take the medicine with food.
Feeling nervous or on edge.
  • This will probably go away soon.
  • If it lasts, ask your doctor if you can lower your dose.
Sexual problems.
  • Ask your doctor if you can take a lower dose.
  • Ask your doctor if there is another medicine you can try.
Sleep problems.
  • Avoid caffeine, nicotine, and alcohol.
  • Don't exercise in the late afternoon or evening.
  • Keep your bedroom quiet, dark, and cool. Use a sleep mask and earplugs.
  • Change the time of day you take your medicine to the morning.
  • If these problems don't go away over time, ask your doctor about lowering your dose.

Medicine Interactions

The biggest danger when you take many medicines is an interaction.

  • A medicine may make another medicine stronger or weaker. For instance, a blood thinner makes bleeding more likely. If you also take aspirin, you make bleeding even more likely. And that could be harmful.
  • A medicine may cause side effects that create problems with other medicines. For instance, a medicine you take to control your urine may affect one you take for dementia.
  • A medicine you take for one health problem can make another health problem worse. For instance, a medicine you use for a cold could make high blood pressure worse.
  • A medicine or interaction can make some common problems worse. This happens most often in older adults. Medicines can make you fall or feel dizzy or confused. You may have trouble sleeping or feel depressed.

Interactions can happen with:

  • Prescription medicines.
  • Over-the-counter (OTC) medicines.
  • Natural health products (vitamins, minerals, and herbs).
  • Foods and drinks.

Learn more

Using Medicines Safely

Medicines are an important part of treatment for many health problems. But for them to help you the most, you have to take them the right way. To do this, you need to know your medicines. And you need to take them safely.

Know your medicines

  • Talk to your doctors. Make sure you know why you are taking each medicine.
  • Make a master list of all your medicines. Write down the medicine names and doctors' names. Include doses and side effects too. And write down why you take each medicine. Include all prescription and over-the-counter medicines and natural health products. Keep this list up to date. Take a copy to each doctor visit.
  • Know when you will run out of each medicine. Ask your pharmacist if there are ways the drugstore can remind you to refill your medicines so you do not run out. Write refill reminders on your calendar. Don't wait until you have a few pills left.
  • Ask your pharmacist to plan your refills so that you can pick up all your medicines at the same time. This can mean fewer trips to the drugstore.

Be safe

  • Talk with your pharmacist or doctor before you take a new prescription, over-the-counter medicine, or natural health product. Ask about side effects and interactions (how your medicines might react with each other). And find out what you can do about them.
  • If you are having a side effect or think a side effect may be caused by an interaction, talk to your doctor or pharmacist. They will help you figure out how to adjust your medicines to avoid the problem.
  • Ask your doctor or pharmacist to run your medicine list through a drug interaction checker. This checks for medicines that can cause problems when taken together. If you find a problem, talk to your doctor.
  • Use one drugstore or pharmacy, if you can. The pharmacist will know which medicines you take. The pharmacist will watch for problems.
  • If side effects bother you and you wonder if you should keep taking a medicine, call your doctor. Your doctor may be able to lower your dose or change your medicine.
  • If you have had a bad allergic reaction to a medicine before and are exposed to it again, watch for symptoms. Treat any symptoms as an emergency. Even if the symptoms are mild at first, they may quickly become very severe.

Take your medicines the right way

  • Be safe with medicines. Take your medicines exactly as prescribed. Call your doctor or nurse advice line if you think you are having a problem with your medicine.
  • Make a daily schedule of your medicines. Put your schedule someplace where you will always see it. Make sure it is easy to find.
  • Use a pillbox. You can buy small pillboxes with just a few compartments. Or you can buy larger ones. If you use a pillbox, keep one pill in its original bottle. Then if you forget what a pill is for, you can find the bottle it came from.
  • Remind yourself. Get sticky notes, and make reminders to take your medicine. Post them near clocks or on the bathroom mirror. Use a wristwatch with an alarm. You can set it for the time you need to take your medicine. Or use an alarm or reminder app on your smartphone.
  • Take the medicine when you do a daily task. For instance, you can take it when you brush your teeth or make your coffee.
  • Talk with your doctor about what you should do if you miss a dose. Find out what to do for each medicine. It may be different for each one.

Learn more



Current as of: February 28, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

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