Penicillins are one of a group of antibiotics that kill bacteria or prevent their growth. There are several types of penicillins, each used to treat different kinds of infections, such as skin, dental, ear, respiratory tract, urinary tract, and other bacterial infections. These drugs will not work for colds, flu, and other infections caused by viruses.

Examples of penicillins are penicillin V (Beepen-VK, Pen-Vee K, V-cillin K, Veetids) and amoxicillin (Amoxil, Polymox, Trimox, Wymox). Penicillins are sometimes combined with other ingredients called beta-lactamase inhibitors, which protect the penicillin from bacterial enzymes that may destroy it before itcan do its work.

Penicillins are available only with a physician's prescription and are sold in capsule, tablet (regular and chewable), liquid, and injectable forms. The recommended dosage depends on the type of penicillin, the strength of the medication, and the medical problem for which it is being taken.

Penicillins must always be taken exactly as directed and should not be discontinued, even if symptoms improve. Following a physician's instructions carefully is important with all types of infections but is especially important with "strep" infections, which can lead to serious heart problems if the infection is not cleared up completely. In addition, different types of penicillinscannot be substituted for one another. Penicillins work best when they are atconstant levels in the blood. To help keep levels constant, the medication should be taken in doses spaced evenly through the day and night. Doses shouldnot be skipped. Some penicillins, notably penicillin V, are taken on an empty stomach; others may be taken with food. When taking penicillin, symptoms generally begin to improve within a few days after initiating treatment.

Penicillins may, however, cause problems such as diarrhea. Severe symptoms may indicate a potentially serious side effect. Penicillins may also alter theresults of some medical tests or adversely interact with other medications. Also, people with hay fever, asthma, eczema, or other general allergies (or who have had such allergies in the past) may be more likely to have severe reactions to penicillins. Thus, it is important for the patient to inform his orher physician of any medications currently being used, of any medical conditions, or of any allergies to foods, dyes, preservatives, or other substances before taking penicillin.

The most common side effects of penicillin are mild diarrhea, headache, vaginal itching and discharge, sore mouth or tongue, or white patches in the mouthor on the tongue. These problems usually dissipate as the body adjusts to the drug and usually do not require medical treatment unless they continue or are bothersome.

More serious side effects are not common, but may occur. These include shortness of breath or rapid or irregular breathing; fever; sudden lightheadednessor faintness; joint pain; skin rash, hives, itching, or red, scaly skin; or swelling or facial puffiness.

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