Health Guide
Drug Guide

Penicillin (Oral route, injection route, intravenous route, intramuscular route)

Brand Names:

Dosage Forms:

Uses of This Medicine:

Penicillins are used to treat infections caused by bacteria. They work by killing the bacteria or preventing their growth.

There are several different kinds of penicillins. Each is used to treat different kinds of infections. One kind of penicillin usually may not be used in place of another. In addition, penicillins are used to treat bacterial infections in many different parts of the body. They are sometimes given with other antibacterial medicines (antibiotics). Some of the penicillins may also be used for other problems as determined by your doctor. However, none of the penicillins will work for colds, flu, or other virus infections.

Penicillins are available only with your doctor's prescription.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, penicillins are used in certain patients with the following medical conditions:

Before Using This Medicine:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Children

Many penicillins have been used in children and, in effective doses, are not expected to cause different side effects or problems in children than they do in adults.

Some strengths of the chewable tablets of amoxicillin contain aspartame, which is changed by the body to phenylalanine, a substance that is harmful to patients with phenylketonuria.

Older adults

Penicillins have been used in the elderly and have not been shown to cause different side effects or problems in older people than they do in younger adults.

Pregnancy

Penicillins have not been studied in pregnant women. However, penicillins have been widely used in pregnant women and have not been shown to cause birth defects or other problems in animal studies.

Breast-feeding

Penicillins pass into the breast milk. Even though only small amounts may pass into breast milk, allergic reactions, diarrhea, fungus infections, and skin rash may occur in nursing babies.

Other medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking any of these medicines, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using medicines in this class with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Other interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems

The presence of other medical problems may affect the use of medicines in this class. Make sure you tell your doctor if you have any other medical problems, especially:

Proper Use of This Medicine:

Penicillins (except bacampicillin tablets, amoxicillin, penicillin V, pivampicillin, and pivmecillinam) are best taken with a full glass (8 ounces) of water on an empty stomach (either 1 hour before or 2 hours after meals) unless otherwise directed by your doctor.

For patients taking amoxicillin, penicillin V, pivampicillin, and pivmecillinam:

For patients taking bacampicillin:

For patients taking penicillin G by mouth:

For patients taking the oral liquid form of penicillins:

For patients taking the chewable tablet form of amoxicillin:

To help clear up your infection completely, keep taking this medicine for the full time of treatment, even if you begin to feel better after a few days. If you have a ”strep” infection, you should keep taking this medicine for at least 10 days. This is especially important in ”strep” infections. Serious heart problems could develop later if your infection is not cleared up completely. Also, if you stop taking this medicine too soon, your symptoms may return.

This medicine works best when there is a constant amount in the blood or urine. To help keep the amount constant, do not miss any doses. Also, it is best to take the doses at evenly spaced times, day and night . For example, if you are to take four doses a day, the doses should be spaced about 6 hours apart. If this interferes with your sleep or other daily activities, or if you need help in planning the best times to take your medicine, check with your health care professional.

Make certain your health care professional knows if you are on a low-sodium (low-salt) diet. Some of these medicines contain enough sodium to cause problems in some people.

Dosing

The dose medicines in this class will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

The number of tablets or teaspoonfuls of suspension that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking a penicillin.

Missed dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Precautions While Using This Medicine:

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

Penicillins may cause diarrhea in some patients.

Oral contraceptives (birth control pills) containing estrogen may not work properly if you take them while you are taking ampicillin, amoxicillin, or penicillin V. Unplanned pregnancies may occur. You should use a different or additional means of birth control while you are taking any of these penicillins. If you have any questions about this, check with your health care professional.

For diabetic patients:

Before you have any medical tests, tell the doctor in charge that you are taking this medicine. The results of some tests may be affected by this medicine.

Side Effects of This Medicine:

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Stop taking this medicine and get emergency help immediately if any of the following effects occur:

Less common
Fast or irregular breathing
fever
joint pain
lightheadedness or fainting (sudden)
puffiness or swelling around the face
red, scaly skin
shortness of breath
skin rash, hives, itching

Check with your doctor immediately if any of the following side effects occur:

Rare
Abdominal or stomach cramps and pain (severe)
abdominal tenderness
convulsions (seizures)
decreased amount of urine
diarrhea (watery and severe), which may also be bloody
mental depression
nausea and vomiting
pain at place of injection
sore throat and fever
unusual bleeding or bruising
yellow eyes or skin
Rare
(For penicillin G procaine only)
Agitation or combativeness
anxiety
confusion
fear of impending death
feeling, hearing, or seeing things that are not real

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
Diarrhea (mild)
headache
sore mouth or tongue
vaginal itching and discharge
white patches in the mouth and/or on the tongue

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.


Last Updated: 10/12/2016

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