Find information on medical topics, symptoms, drugs, procedures, news and more, written in everyday language.

* This is the Consumer Version. *

Aging and Drugs

by J. Mark Ruscin, PharmD

Drugs, the most common medical intervention, are an important part of medical care for older people. Without drugs, many older people would function less well or die at an earlier age.

Did You Know...

  • Up to half of older people do not take drugs as directed by their doctor.

  • Older people are more susceptible to the effects (and side effects) of many drugs.

Older people tend to take more drugs than younger people because they are more likely to have chronic disorders such as high blood pressure, diabetes, and arthritis. Most drugs used by older people for chronic disorders are taken for years. Other drugs may be taken for only a short time to treat such problems as infections, some kinds of pain, and constipation. On average, older people take four or five prescription drugs and two nonprescription (over-the-counter, or OTC) drugs each day. Many OTC drugs are potentially hazardous for older people (see Older People).

Benefits and Risks

Many of the improvements in the health and function of older people during the past several decades can be attributed to drugs.

  • Vaccines help prevent many infectious diseases (such as influenza and pneumonia) that once killed many older people.

  • Antibiotics are often effective in treating pneumonia—once known as the killer of older people—and many other serious infections.

  • Drugs to control high blood pressure (antihypertensives) help prevent strokes and heart attacks.

  • Drugs to control blood sugar levels (antihyperglycemic drugs) enable millions of people with diabetes to lead normal lives. These drugs also reduce the risk of eye and kidney problems that diabetes can cause.

  • Drugs to control pain and other symptoms enable millions of people with arthritis to continue to function.

However, drugs can have effects that are not intended or desired (side effects). Starting in late middle age, the risk of side effects from drugs increases. Older people are more than twice as susceptible to the side effects of drugs as younger people (see Overview of Adverse Drug Reactions). Side effects are also likely to be more severe, affecting quality of life and resulting in visits to the doctor and in hospitalization.

Older people are more susceptible to side effects for several reasons:

  • As people age, the amount of water in the body decreases, and the percentage of fat tissue increases. Thus, in older people, drugs that dissolve in water reach higher concentrations because there is less water to dilute them, and drugs that dissolve in fat accumulate more because there is relatively more fat tissue to store them.

  • As people age, the kidneys are less able to excrete drugs into urine, and the liver is less able to break down (metabolize) many drugs (see Drug Metabolism). Thus, drugs are less readily removed from the body.

  • Older people take more drugs and have more disorders.

  • Fewer studies have been done in older people to help identify appropriate doses of drugs.

Because of these age-related changes, many drugs tend to stay in an older person’s body much longer, prolonging the drug’s effect and increasing the risk of side effects. Therefore, older people often need to take smaller doses of certain drugs or perhaps fewer daily doses. For example, digoxin, a drug commonly used to treat certain heart disorders, dissolves in water and is eliminated by the kidneys. Because the amount of water in the body decreases and the kidneys function less well as people age, digoxin concentrations in the body may be increased, resulting in side effects (such as nausea or abnormal heart rhythms). To prevent this problem, doctors may use a smaller dose. Or sometimes other drugs can be substituted.

Older people are more sensitive to the effects of many drugs. For example, older people tend to become sleepier and are more likely to become confused when using antianxiety drugs or sleep aids to treat insomnia. Drugs that lower blood pressure by widening (dilating) arteries and reducing the amount of work the heart has to do tend to lower blood pressure much more dramatically in older people than in the young. Knowing which drugs are particularly likely to cause problems in older people helps avoid side effects, such as dizziness, light-headedness, and falls. Older people who are taking these drugs can ask their doctor about changing to a different drug.

Many commonly used drugs have anticholinergic effects. These drugs include some antidepressants, many antihistamines (contained in OTC sleep aids, cold remedies, and allergy drugs), and diphenhydramine (used in the treatment of insomnia). Older people are particularly susceptible to anticholinergic effects, which include confusion, blurred vision, constipation, dry mouth, light-headedness, difficulty starting and continuing to urinate, and loss of bladder control (urinary incontinence). Some anticholinergic effects, such as reduction of tremor (as in the treatment of Parkinson’s disease) and reduction of nausea, are desirable, but most are not.

A drug may have a side effect because it interacts with

  • A disease other than the one for which the drug is being taken (drug-disease interaction)

  • Another drug (drug-drug interaction)

  • Food (drug-food interaction)

  • A medicinal herb (drug–medicinal herb interaction—see see Some Possible Medicinal Herb–Drug Interactions)

Because older people tend to have more diseases and take more drugs than younger people, they are more likely to have drug-disease and drug-drug interactions. Patients, doctors, and pharmacists can take steps to reduce the risk of these interactions (see How to Reduce the Risk of Drug-Drug Interactions). Because OTC drugs and medicinal herbs can interact with other drugs, people should ask their doctor or pharmacist about these drugs as well as about prescription drugs.

Not following a doctor’s directions for taking a drug (noncompliance or nonadherence) can be risky (see see Adherence to Drug Treatment). Old age alone does not make people less likely to take drugs as directed. However, up to half of older people do not do so. Not taking a drug, taking too little, or taking too much can cause problems. Taking less of a drug because it has side effects may seem reasonable, but people should talk to a doctor before they make any changes in the way they take a drug.

Remembering to Take Drugs

To benefit from taking drugs, people must remember not only to take the drugs but also to take them at the right time and in the right way. When several drugs are taken, the schedule for taking them can be complex. For example, drugs may have to be taken at different times throughout the day to avoid interactions. Some drugs may have to be taken with food. Other drugs have to be taken when no food is in the stomach. The more complex the schedule, the more likely people are to make mistakes following it. For example, bisphosphonates (such as alendronate and risedronate), which are used to increase bone density, need to be taken on an empty stomach and with only water (at least a full glass). If these drugs are taken with other liquids or food, they are not absorbed well and do not work effectively.

If older people have memory problems, following a complex schedule is even harder. Such people usually need help, often from family members. The doctor can be asked about simplifying the schedule. Often, doses can be rescheduled to make taking the drugs more convenient or reduce the total number of daily doses.

Memory aids can help older people remember to take their drugs. For example, using a drug can be associated with a specific daily task, such as eating a meal.

A pharmacist can provide containers that help people take drugs as instructed. Daily doses for 1 week or 2 weeks may be packaged in a plastic pack marked with the days or with the times of the day, so that people can keep track of doses taken by noting the empty spaces. Some pharmacies can package drugs in blister packs, so that the daily dose can be easily removed and kept track of. However, such packaging may cost a little more.

More elaborate containers with a computerized reminder system are available. These containers beep or flash at dosing time. Another alternative is a paging service with a beeper. This service is available from subscriber-based telecommunications companies.

Some Drugs Particularly Likely to Cause Problems in Older People





To treat depression

Amitriptyline has strong anticholinergic effects.* It also causes excessive drowsiness.

Antihistamines that have anticholinergic effects (such as chlorpheniramine, cyproheptadine, dexchlorpheniramine, diphenhydramine, hydroxyzine, orphenadrine, promethazine, and tripelennamine)

To relieve allergy symptoms, to aid sleep, or to relieve cold symptoms

All nonprescription (over-the-counter) and many prescription antihistamines have strong anticholinergic effects.* Antihistamines are commonly included with other drugs in cough and cold preparations.

Antipsychotic drugs (such as chlorpromazine, haloperidol, mesoridazine, thioridazine, and thiothixene)

To treat loss of contact with reality (psychosis) or, somewhat controversially, to treat behavioral disturbances in people with dementia

Antipsychotic drugs can cause drowsiness, movement disorders (that resemble Parkinson’s disease), and uncontrollable facial twitches. These drugs also have anticholinergic effects.* Some side effects are potentially fatal. Antipsychotic drugs should be used only when a psychotic disorder is present.

Barbiturates (such as phenobarbital and secobarbital)

To calm, to relieve anxiety, or to aid sleep

Barbiturates have more side effects than other drugs used to treat anxiety and insomnia. They also interact with many other drugs. Generally, older people should take barbiturates only as treatment for a seizure disorder.

Benzodiazepines that have long-lasting effects (such as chlordiazepoxide, clorazepate, diazepam, flurazepam, halazepam, nitrazepam, and quazepam)

To calm, to relieve anxiety, or to aid sleep

The effects of these drugs last a very long time (often more than several days) in older people. These drugs can cause prolonged drowsiness and loss of balance when a person is walking. Thus, the risk of falls and fractures is increased.


To treat diabetes

This drug’s effects last a long time. In older people, chlorpropamide can lower blood sugar levels (causing hypoglycemia) for several hours. This drug can also lower the sodium level in the blood (causing hyponatremia). A low sodium level can lead to changes in personality, confusion, and sluggishness (lethargy).


To treat heartburn, indigestion, or ulcers

Typical doses of cimetidine, a histamine-2 (H 2 ) blocker, may have side effects, especially confusion.


To treat heart failure or abnormal heart rhythms (arrhythmias)

As people age, the kidneys are less able to excrete digoxin. Large doses of the drug can more easily reach harmful (toxic) levels. Side effects may include loss of appetite, nausea, and confusion.

Dipyridamole (immediate-release)

To reduce the risk of blood clots or to improve blood flow

Dipyridamole frequently causes low blood pressure when older people stand up. It can also increase the risk of bleeding when it is taken with other drugs that make blood less likely to clot, such as aspirin or the anticoagulant warfarin.


To treat abnormal heart rhythms

Disopyramide has strong anticholinergic effects.* It may cause heart failure in older people.


To treat depression

Doxepin has strong anticholinergic effects.* It also causes excessive drowsiness.

Drugs that reduce or stop muscle spasms in the digestive tract (antispasmodic drugs, such as belladonna alkaloids, clidinium/chlordiazepoxide, dicyclomine, hyoscyamine, and propantheline)

To relieve abdominal cramps and pain

These drugs have strong anticholinergic effects* and are toxic in older people. Their usefulness—especially at the low doses tolerated by older people—is questionable.

Estrogens only (oral)

To help relieve menopausal symptoms, such as hot flashes, night sweats, and vaginal dryness

Estrogens increase the risk of breast and uterine (endometrial) cancer and may increase the risk of stroke and heart attack in older women.


To treat heartburn, indigestion, or ulcers

To some extent, high doses of famotidine, an H 2 blocker, may have side effects, especially confusion.


To treat depression

Fluoxetine’s effects last a long time. It may cause sleep disturbances, restlessness, and increased agitation. It may also decrease appetite in some older people who do not need to lose weight.


To relieve pain

Of all nonsteroidal anti-inflammatory drugs (NSAIDs), indomethacin affects the brain the most. It can cause confusion or dizziness.

Iron supplements (such as ferrous sulfate)

To provide supplemental iron

Doses higher than 325 milligrams daily do not greatly increase the amount of iron that is absorbed, and such doses are more likely to cause constipation.


To relieve pain

Meperidine, an opioid, often causes confusion. Like all opioids, it may cause constipation, retention of urine, drowsiness, and confusion. When taken by mouth, meperidine is not very effective.


To lower high blood pressure

Methyldopa may slow the heart rate and worsen depression.

Muscle relaxants (such as carisoprodol, chlorzoxazone, cyclobenzaprine, metaxalone, methocarbamol, and oxybutynin)

To relieve muscle spasms

Most muscle relaxants have anticholinergic effects.* They also cause drowsiness and weakness. The usefulness of all muscle relaxants at the low doses tolerated by older people is questionable.


To treat heartburn, indigestion, or ulcers

To some extent, high doses of nizatidine, an H 2 blocker, may have side effects, especially confusion.

Non–COX-selective nonsteroidal anti-inflammatory drugs (NSAIDs, such as naproxen, oxaprozin, and piroxicam)

To relieve pain and inflammation

Long-term use of the maximum dosage may cause kidney problems or bleeding from the stomach or intestine.


To relieve pain

Pentazocine, an opioid, is more likely to cause confusion and hallucinations than other opioids. Like all opioids, it may cause constipation, retention of urine, drowsiness, and confusion.

Propoxyphene and combination products that include it

To relieve pain

Propoxyphene, an opioid, provides no more pain relief than acetaminophen. Like all opioids, it may cause constipation, retention of urine, drowsiness, and confusion.


To treat heartburn, indigestion, or ulcers

To some extent, high doses of ranitidine, an H 2 blocker, may have side effects, especially confusion.


To lower high blood pressure

Reserpine can cause dizziness when a person stands up, depression, drowsiness, and erectile dysfunction (impotence).


To relieve nausea

This drug can cause abnormal movements of the arms, legs, and other parts of the body. It is one of the least effective drugs for relieving nausea.

*Anticholinergic effects include confusion, blurred vision, constipation, dry mouth, light-headedness, difficulty starting and continuing to urinate, and loss of bladder control.

Dipyridamole is also available in an extended-release formulation with aspirin. This product, which is used to prevent strokes in people who have had a stroke, is not included in this list.

Resources In This Article

Drugs Mentioned In This Article

  • Generic Name
    Select Brand Names
  • No US brand name
  • AXID
  • No brand name
  • SOMA