Penicillins : How to Take Your Medicine

by Food and Drug Administration (FDA)

How you take a drug makes a big difference in how well it works and how safe it will be for you. Sometimes it can be almost as important as what you take. Timing, what you eat and when you eat, proper dose, and many other factors can mean the difference between getting better, staying the same, or even getting worse. This drug information page is intended to help you make your treatment work as well as possible. It is important to note, however, that this is only a guideline. You should talk to your doctor or pharmacist about how and when to take any prescribed drug.

This second in a series of articles on commonly prescribed drugs is about penicillins.

Penicillin, the world's first antibiotic, was discovered by British scientist Alexander Fleming in 1928. But it was not used until World War II, when the need for a treatment for injuries and infectious disease became desperate and penicillin was speeded into production in the United States.

By 1945 penicillin was in widespread use. In the years that followed, together with other antibiotics, it decreased the incidence and severity of many infectious diseases, such as pneumonia, tuberculosis and diphtheria.

In addition to their ability to treat infectious diseases, the ability of antibiotics to control infection made possible cardiac surgery, organ transplants, and treatment of severe burns.

Conditions Penicillins Treat

Penicillins work by killing bacteria or preventing their growth. Today there are at least 20 kinds of penicillin (see box). Penicillins are used to treat many different kinds of infection. For example, they are used to treat ear, nose and throat infections, respiratory and urinary tract infections, prostate infections, and certain sexually transmitted diseases. Penicillins are used to prevent bacterial infection before, during and after surgery and to prevent Group A streptococcus ("strep") infections in people with a history of rheumatic heart disease.

None of the penicillins work for colds, flu, or other virus infections.

How to Take

Penicillins come in liquid, tablet and injectable forms. When taking the liquid form, be sure to measure the amount accurately. Liquid doses are best measured in special spoons available from your pharmacist. Teaspoons or tablespoons from the kitchen drawer are rarely the correct dosage size. Chewable tablets should be chewed or crushed before swallowing to insure rapid absorption into the blood.

Most penicillins work best when taken on an empty stomach (either one hour before meals or two hours after) with an 8-ounce glass of water. The water helps prevent the medicine from irritating the delicate lining of the esophagus and stomach.

However, some types of penicillin can be taken on either a full or empty stomach. These include amoxicillin, amoxicillin combined with clavulanate, penicillin V, and the tablet form of bacampicillin.

Liquid amoxicillin can be taken straight or mixed with other liquids such as infant formulas, fruit juice, milk, water, ginger ale, or other cold drinks. But if you mix amoxicillin with another liquid, be sure to drink it immediately and finish the entire drink to get the full dose of medicine.

Penicillins work best when there is a constant amount circulating in the body. So it's important not to miss a dose. Also, it's best to take doses at evenly spaced intervals, both day and night. For example, if you are supposed to take four doses, they should be spaced about six hours apart. If this presents a problem, such as interrupting sleep or other activities, check with your doctor, nurse or pharmacist before modifying the dosage.

Of special note:

Bottles of carbenicillin tablets usually contain a small packet of a drying agent that keeps the tablets from getting damp and breaking down. The drying agent is not a medicine and should not be swallowed. It should be kept in the bottle until the tablets are gone and then thrown away.

When taking penicillin G, don't drink orange or grapefruit juice or other acidic beverages (such as soft drinks and carbonated water) within an hour of taking the medicine, or the medicine may not work as well.

Don't use any penicillins — or any other medicine — after the expiration date on the label because they may not work properly.

Missed Doses

What should you do if you miss a dose of penicillin?

If it's only been a short time, take it as soon as possible.

However, if it's almost time for your next dose and you're supposed to take two doses a day, space the missed dose and the next dose five to six hours apart.

If it's almost time for your next dose and you're supposed to take three or more doses a day, double the next dose or space the missed dose and the next dose two to four hours apart.

Then resume your regular medicine schedule.

Relief of Symptoms

Penicillins usually stop infections within days. Because they do not relieve symptoms immediately, your doctor may prescribe other medicines, such as aspirin or acetaminophen, to ease pain and fever until the penicillin takes effect. It is important to finish the entire amount of penicillin prescribed — even if you begin to feel better after a few days — to prevent a recurrence of the infection.

If you have a "strep" infection, it is especially important to keep taking the medicine for at least 10 days, or as prescribed by your doctor. Serious heart problems, such as rheumatic fever, could develop later if the infection isn't cleared up completely.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.