Taking Medicines

Side Effects

Older Bodies Handle Drugs Differently

As the body ages, its ability to break down substances can decrease. Because older people may not be able to metabolize drugs as well as they once did, they might need smaller doses of medicine per pound of body weight than young or middle-aged adults do.

Also, older adults frequently take more than one medication at a time. Medicines can interact with each other in unexpected ways, so anyone taking several medications at the same time should be extra careful. (See “Tips to Avoid Side Effects” below.)

Risks and Benefits

All medicines have risks as well as benefits. The benefits of medicines are that they can improve your health and well-being by doing what they were designed for, like treating a disease, curing infection, or relieving pain. The risks are the chances that something unwanted or unexpected will happen when you use medicines. Unwanted or unexpected symptoms or feelings that occur when you take medicine are called side effects.

Side effects can be relatively minor, such as a headache or a dry mouth. They can also be life-threatening, such as severe bleeding or irreversible damage to the liver or kidneys.

Prescription and Over-the-Counter Medicines

There are two major types of medicines: prescription drugs and over-the-counter ones.

  • The medications a doctor prescribes for you are called prescription drugs. You can only pick them up at a pharmacy.
  • Medicines you can get without a doctor's prescription, which you can buy at a grocery or convenience store, are called over-the-counter drugs.

It is important to remember that over-the-counter products include many different substances such as vitamins and minerals, herbal and dietary supplements, laxatives, cold medicines and antacids. Any combination of prescription drugs and over-the-counter substances can interact with each other to cause unexpected or unwanted effects.

Tips to Avoid Side Effects

Stomach upset, including diarrhea or constipation, is a side effect common to many medications. Often, this side effect can be lessened by taking the drug with meals. Always check with your doctor, nurse, or pharmacist to see if you should take a particular medication with food.

Here are some more tips to help you avoid side effects.

  • Always inform your doctor or pharmacist about all medicines you are already taking, including herbal products and over-the-counter medications. Be sure to include products like pain relievers, antacids, alcohol, herbal remedies, food supplements, vitamins, hormones and other substances you might not think are medicines.
  • Tell your doctor, nurse, or pharmacist about past problems you have had with medicines, such as rashes, indigestion, dizziness, or loss of appetite .
  • Ask whether the drug may interact with any foods or other over-the-counter drugs or supplements you are taking.
  • Read the prescription label on the container or the drug information sheet that comes with your medication carefully and follow its directions. Make sure you understand how often, when and how much medicine to take each day.
  • If you experience side effects, write them down so you can report them to your doctor accurately.
  • Call your doctor right away if you have any problems with your medicines or if you are worried that the medicine might be doing more harm than good. He or she may be able to change your medicine to another one that will work just as well.
  • Don't mix alcohol and medicine unless your doctor or pharmacist says it's okay. Some medicines may not work well or may make you sick if taken with alcohol.

Types of Drug Interactions

(The information on drug interactions is drawn from “Medicine and You: A Guide for Older Adults” from the Food and Drug Administration (FDA.)

Drugs can interact with other substances, or even health conditions, in various ways. Drug interactions include

  • drug-drug interactions
  • drug-food interactions
  • drug-condition interactions
  • drug-alcohol interactions.

(Watch this FDA video to learn more about avoiding drug interactions. To enlarge the video, click the brackets in the lower right-hand corner. To reduce the video, press the Escape (Esc) button on your keyboard.)

Drug-drug Interactions

Drug-drug interactions happen when two or more medicines react with each other in your body. The result can be unpredictable and can include unwanted effects, medicines that don’t work properly, or even medicines that become stronger than they should be.

Although it is virtually impossible for doctors to know how every medicine interacts with every other medicine, they do know that certain combinations of drugs cause problems. For example, unless your health care professional tells you to, you should not take aspirin if you are taking a prescription blood thinner, such as Coumadin®, also called warfarin, because the combination of the two drugs could lead to dangerous bleeding. Mixing Viagra®, also called sildenafil, and the heart drug nitroglycerin can cause blood pressure to plunge to dangerously low levels.

Even if a product is not called a drug, your body handles it the same way it handles drugs. Some herbal and other substances can interact in potentially dangerous ways with prescription drugs or other over-the-counter products. For example, ginkgo biloba, a botanical product, can reduce the effectiveness of blood-thinning medications and raise the risk for serious complications such as stroke.

Drug-condition Interactions

Drug-condition interactions happen when a medical condition you already have makes certain drugs potentially harmful. For example, if you have high blood pressure or asthma, taking certain nasal decongestants can cause you to have an unwanted reaction.

Drug-food Interactions

Drug-food interactions occur when drugs react with foods or drinks. In some cases, food in the digestive track can affect how a drug is absorbed. Some medicines also may affect the way nutrients are absorbed or used in the body.

For example, calcium-rich dairy products or certain antacids can prevent antibiotics from being properly absorbed into the bloodstream.

Another example is grapefruit juice. A single glass of grapefruit juice can raise the level of some medications in the blood, which can cause health problems. This can occur with several types of drugs commonly used to treat heart conditions.

Be sure to ask your doctor or pharmacist if it is safe to consume foods or beverages that contain grapefruit with the medication you are taking. You may still be able to enjoy grapefruit or its juice if you consume it at a different time of day than when you take medicine. Your doctor or pharmacist can advise you.

Drug-alcohol Interactions

Drug-alcohol interactions can happen when the medicine you take reacts with an alcoholic drink. For instance, mixing alcohol with some medicines may cause you to feel tired and slow your reactions.

It is important to know that many medicines do not mix well with alcohol. As you grow older, your body may react differently to alcohol, as well as to the mix of alcohol and medicines. Keep in mind that some problems you might think are medicine-related, such as loss of coordination, memory loss, or irritability, could be the result of a mix between your medicine and alcohol.