University of Iowa Health Science Relations and
Beth Phillips, PHARMD
Professor of Pharmacy
First Published: 2000
Last Revised: September 2004
Peer Review Status: Internally Peer Reviewed

Do you take your medications with water or milk? With or without meals?

The answers to these questions could indicate whether your medications are being fully utilized.

Some medications are affected by the type of food or liquid with which they are consumed, says Dr. Beth Phillips, a clinical pharmacy specialist at University of Iowa Hospitals and Clinics.

Some antibiotics, such as tetracycline, are not fully effective when taken with milk or dairy products. The calcium in milk and dairy products can prevent the antibiotics from being absorbed into your bloodstream. Antibiotics are usually best utilized when consumed with water or juices, Phillips says.

"Take the antibiotic one hour before consuming any dairy products," she says. This allows time for the antibiotic to be absorbed from the stomach.

The blood levels of some medications such as certain blood pressure, heart, and cholesterol medications may be increased when consumed with large amounts (several glasses) of grapefruit juice. Patients who eat half of a grapefruit on occasion are generally not consuming enough grapefruit juice to interact with medications, she says. If your diet consists of large amounts of grapefruit juice, ask your pharmacist whether this could affect any medications you are taking.

Drugs such as aspirin, cold tablets and vitamins are best taken with water. Most medication labels indicate whether medications should be taken with or without food.

"There are exceptions to all of these guidelines. If you have any questions about your medication, ask your pharmacist or physician," Phillips cautions.

The form of the drug is also a strong factor in determining the drug's absorption in the body, she says.

Medications in liquid form are absorbed fastest in the bloodstream.

Uncoated tablets--such as the common aspirin--are absorbed more slowly. Stomach juices must break them into small pieces before they can be absorbed through the stomach wall and enter the bloodstream, Phillips says.

Coated tablets are absorbed very slowly into your system. This form of medication is intended to dissolve in the small intestine instead of the stomach where it could cause irritation, she says.

Capsules are absorbed faster in your system than tablets. The medication in capsules is already broken into tiny particles. The gelatin coating surrounding the particles dissolves quickly and allows the medication to be absorbed rapidly into your bloodstream, Phillips says.