Medications Work Differently in Older Adults

Medication dose, as well as information about the effectiveness and side effects of medication, are generally determined by studies done in relatively young, healthy people. This information may not apply to older adults, because our bodies and how we process medications change with age. As we get older, our bodies react to drugs differently than when we were younger.  

The aging process, along with medical conditions, often impacts the benefits and side effects of medications.

Changes in the Body

Drugs go on a complex journey through our body from the time we take our medications until they leave our body.

The aging process can affect how the medication is absorbed, used in the body, and exits the body. Changes that decrease your body’s ability to break down or remove certain medications from your system may mean that medications can stay in your body longer. So, you may need a lower dose of the medication or a different medication that is safer. In most cases, older adults need lower doses of medications than younger adults. You can start with a low dose of a medication then slowly increase to the target amount to receive the same benefit and avoid side effects. This can be done by working closely with your healthcare provider.

Studies also show that certain medications are less safe for older people, and it is important that you work with your provider or pharmacist to use medications that are safe for your age. The American Geriatrics Society’s Beers Criteria lists medications that may not be safe in older people and can be used as a tool when you talk with your provider or pharmacist about using safe medications.

When taking medications, it is important to make sure that:

  • The correct medication is prescribed for the correct condition
  • The medication is right for you, your age, and your conditions
  • You take the proper dose for the length of time your healthcare provider prescribes

Multiple Medical Conditions

Older adults often have multiple medical conditions. These may affect how medications work in the body. Medications used to treat one condition may also make another condition worse. For example, older adults with memory problems may have worsening symptoms caused by medicines used to treat their other conditions. Therefore, it is important that all providers who prescribe medications for you know about all of the medical conditions you have. Also, be sure to let the prescriber know if a medication they gave you worsens any of your conditions.

Effects of Food and Beverages on Medications

Medications may be affected by food, beverages, and supplements or medicines that you take at the same time. For example, some antibiotics are not absorbed well when taken with foods, beverages, or medicines that contain calcium, magnesium, or iron (such as antacids, vitamins, or dairy products). Certain foods, such as grapefruit juice, can also change the metabolism of certain medications. This may cause the medicine to build up in the body. You can ask your pharmacist about what foods, beverages or supplements to avoid when you pick up your medications.

Medication Interactions

A medication interaction is a reaction between two (or more) medications or between a medication and food, beverage, supplement, or herbal product. A medication interaction can make a drug’s effect stronger, weaker, or cause unwanted side effects. An older person may be on multiple medications to treat the many conditions they have and also use over-the-counter (OTC) medicines, vitamins, other supplements or herbal products.  The more medications and other products you are on, the greater the chances of having a medication interaction. Be sure to let your provider and pharmacist know about all prescription and other medicines you use at home, so they can check on interactions for you.  

Other Factors

Other factors may affect how the body deals with medications. For example, a medication's effect can be affected by cigarette smoking, drinking caffeinated or alcoholic beverages, changes in diet, changes in medical conditions, and viral infections.

Common side effects of medicines in older adults can be dizziness and falls, weight loss or weight gain, and changes in memory or our ability to think and process information.  These, in turn, can cause older adults to get hurt and may ultimately lessen their ability to function in day-to-day life. Be sure to let your providers know about these other factors and any changes you have.


Many older adults cope with more than one medical condition at the same time. Often, managing multiple conditions can mean that the older adult may need many different medications.

When older adults take five or more medicines, it is called “polypharmacy.” With polypharmacy, the medicines may interact with each other and with your body in harmful ways. For example, the medications can increase negative side effects or decrease benefits.

Many older adults take multiple medications from different prescribers. It is important to provide a list of your current medications, including any OTC medicines, vitamins, supplements, or herbal products you use, to each provider so they can update their records. This practice can help prevent harmful side effects and decrease unnecessary medications and interactions.

Tell your healthcare providers about all of the medicines you are taking, no matter which provider prescribed them to you. Do not forget to include OTC medications, vitamins, supplements, and herbal products on your medication list.

Discuss OTC medications, vitamins, supplements, and herbal products, as well as any prescriptions given by other healthcare providers. Then you and your provider can figure out whether one or more drugs can be changed or stopped.

Also, if you have experienced an unwanted symptom (such as having had a fall or having memory problems), be sure to tell your healthcare provider - and ask if this could be caused by one of your medicines.

Prescribing Cascade

Polypharmacy increases the possibility of a “prescribing cascade.” A prescribing cascade is when a side effect of one medication is mistaken for a new medical condition and is then treated with another medication. This can lead to being prescribed more medications than you need and also further increases your risk of having more side effects and continuing the cascade. Therefore, ask your healthcare provider to review all of your medicines with you. And before you get a new medicine, ask if one of the medicines you are already taking might be causing the problem the new medicine is meant to treat.


Last Updated August 2020