Topic Overview

Medicines are a big part of treatment for many health problems. They fight harmful bacteria, relieve pain, and save lives. Medicines have helped cure diseases that used to have no cure.

But there is a downside to medicines.

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.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them.

Here are some important things to think about:

• 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. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.
• Call your doctor or 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.

  These are signs of a severe allergic reaction to the medicine.

Will you get side effects?

Anyone can feel side effects from a medicine, but 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, how much you weigh, whether you are male or female, and what other health problems you may 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. A medicine you've often taken without getting side effects may suddenly cause side effects. Or side effects may stop.

What can you do to prevent 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 they 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 this.
• Whether you need any tests to check for them.
• 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.

What can you do for mild side effects?

In general, you can ask your doctor if you can take less of the medicine or try another one.

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

Medicine Interactions

Taking certain medicines together may cause a bad reaction. This is called an interaction. For example, one medicine may cause side effects that create problems with other medicines. Or one medicine may make another medicine stronger or weaker.

A medicine you take for one health problem also can make another health problem worse. For example, a medicine you use for a cold could make high blood pressure worse.

Interactions can happen among any of these:

• Prescription medicines
• Over-the-counter (OTC) medicines
• Vitamin and mineral supplements
• Herbal remedies
• Food and drink
• Illegal drugs

If you have several doctors, and if some of them don't know all of the medicines you're taking, a bad reaction can be mistaken as an illness. For example, some medicines can cause memory problems that are mistaken for dementia. Falls can be a sign of too much medicine, rather than frailty.

But just because you take several medicines doesn't mean you'll have problems. To be safe, make sure that all your doctors know you're taking medicines prescribed by another doctor and about over-the-counter medicines, natural health products, and illegal drugs you take.

How do you know you're having a medicine interaction?

It is hard to know whether you're having a side effect or interaction. If you've talked with your doctor about it, you may be able to recognize the symptoms of an interaction. How likely you are to have an interaction depends on how many medicines you're taking, how much of a medicine you take, how old you are, how much you weigh, whether you are male or female, and what other health problems you may have.

If you think that you are having an interaction, talk to your doctor or pharmacist. He or she will review the medicines you are taking to see if there is a problem. Your doctor or pharmacist can make suggestions to help an interaction while still making sure that you're getting the treatment you need.

Using Medicines Safely

Here are some things you can do to be sure that you're taking medicines safely.

Make a list of all the medicines you take, and update it every time you get a new medicine. Use this form to track your medicines. If you stop taking a medicine, take it off your list. Keep a copy in your purse or wallet, and take it with you each time you see your doctor or see a new doctor. Have each doctor keep in your file a copy of your list of medicines.

Include herbal and dietary supplements, vitamins, and over-the-counter medicines on your list, because they can cause problems when you take them with some medicines. For example, ginkgo biloba, some types of ginseng, and large amounts of garlic may make bleeding more likely. That means they could be dangerous when taken with other medicines that may cause bleeding, like blood thinners or non-steroidal anti-inflammatory drugs (NSAIDS), such as ibuprofen.

Talk with your pharmacist or doctor before you take a new prescription, over-the-counter medicine, or supplement. It may be helpful to schedule a visit or call your pharmacist ahead of time to let him or her know that you want to talk about the medicines you take. Talk about:

• All the medicines, over-the-counter medicines, and natural health products you take.
• Possible interactions with any other medicine you take.
• What to do if you think you are having an adverse reaction. Ask about who you should call and what you will need to do right away.
• Any health problems that you have.

Take your medicines as your doctor or the
instructions
say. This will make sure you get the most benefit, and it will help you avoid interactions and side effects. Be sure you know how much to take, when to take it, and whether you can take the medicine with food, drink, or alcohol. Also be sure you know what to do if you miss a dose. This applies to prescription or over-the-counter medicines, and natural health products. For more information, see Taking Medicines as Prescribed.

Use a drug interaction checker. Ask your doctor or pharmacist to run your medicine list through a drug interaction checker. This checks for medicines that can have bad interactions. If you find a problem, talk to your doctor.

Use one drugstore or pharmacy, if possible. The pharmacist will know which medicines you take and will watch for interactions. If you fill prescriptions at more than one pharmacy, make sure that each of them has the same information about your medicines.

Know which medicines to avoid. Because of possible bad reactions, some people may need to avoid some medicines. For example, if you have heart failure and are taking digoxin, you may have problems with clarithromycin—an antibiotic used for pneumonia—because it increases the effect of digoxin. Your doctor and pharmacist will check for drug interactions and help you know what medicines are safe to take.

Even something that seems as harmless as grapefruit juice can change how your body uses medicines. Cholesterol-lowering medicines (statins) and high blood pressure medicines are two examples of medicines that grapefruit juice affects. If you take these medicines, your doctor may suggest that you don't drink grapefruit juice. For more information, see the topic Grapefruit Juice and Medicines.