Tetracyclines Health Article

Definition

Tetracyclines are medicines that kill certain infection-causing microorganisms.

Purpose

Tetracyclines are called "broad-spectrum" antibiotics, because they can be used to treat a wide variety of infections. Physicians may prescribe these drugs to treat eye infections, pneumonia, gonorrhea, Rocky Mountain spotted fever, urinary tract infections, and other infections caused by bacteria. The medicine is also used to treat acne. The tetracyclines will not work for colds, flu, and other infections caused by viruses.

Description

Tetracyclines are available only with a physician's prescription. They are sold in capsule, tablet, liquid, and injectable forms. Some commonly used medicines in this group are tetracycline (Achromycin V, Sumycin) and doxycycline (Doryx, Vibramycin).

Recommended dosage

The recommended dosage depends on the type of tetracycline, its strength, and the type and severity of infection for which it is being taken. Check with the physician who prescribed the drug or the pharmacist who filled the prescription for the correct dosage.

To make sure the infection clears up completely, take the medicine for as long as it has been prescribed. Do not stop taking the drug just because symptoms begin to improve.

Tetracyclines work best when they are at constant levels in the blood. To help keep levels constant, take the medicine in doses spaced evenly through the day and night. Do not miss any doses.

This medicine works best when taken on an empty stomach, with a full glass of water. The water will help prevent irritation of the stomach and esophagus (the tube-like structure that runs from the throat to the stomach). If the medicine still causes stomach upset, it may be necessary to take it with food. However, tetracyclines should never be taken with milk or milk products, as these may prevent the medicine from working properly. Do not drink or eat milk or dairy products within one to two hours of taking tetracyclines (except doxycycline and minocycline).

Precautions

Taking outdated tetracyclines can cause serious side effects. Do not take this medicine if:

• its color, appearance, or taste have changed
• it has been stored in a warm or damp area
• the expiration date on its label has passed flush any such medicine down the toilet, if there is any question about whether the medicine is still good, check with a physician or pharmacist

Do not take antacids, calcium supplements, salicylates such as Magan or Trilisate, magnesium-containing laxatives, or sodium bicarbonate (baking soda) within one to two hours of taking tetracyclines.

Do not take any medicines that contain iron (including multivitamin and mineral supplements) within two to three hours of taking tetracyclines.

Some people feel dizzy when taking these drugs. The medicine may also cause blurred vision. Because of these possible effects, anyone who takes these drugs should not drive, use machines or do anything else that might be dangerous until they have found out how the drugs affect them.

Birth control pills may not work properly while tetracyclines are being taken. To prevent pregnancy, use alternative methods of birth control while taking tetracyclines.

This medicine may increase sensitivity to sunlight. Even brief exposure to sun can cause a severe sunburn or a rash. While being treated with this medicine, avoid being in direct sunlight, especially between 10 A.M. and 3 P.M.; wear a hat and tightly woven clothing that covers the arms and legs; use a sunscreen with a skin protection factor (SPF) of at least 15; protect the lips with a sun block lipstick; and do not use tanning beds, tanning booths, or sunlamps. The sensitivity to sunlight and sunlamps may continue for two weeks to several months after stopping the medicine, so continue to be careful about sun exposure.

Tetracyclines may permanently discolor the teeth of people who took the medicine in childhood. The drugs may also slow down the growth of children's bones. Do not give tetracyclines to infants or children under 8 years of age unless directed to do so by the child's physician.