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You are here : 3-RX.com > Drugs & Medications > Detailed Drug Information (USP DI) > Penicillins : Before Using

Penicillins (Systemic)

Penicillins | Before Using | Proper Use | Precautions | Side Effects | Additional Information

Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For penicillins, the following should be considered:

Allergies - Tell your doctor if you have ever had any unusual or allergic reaction to any of the penicillins or cephalosporins. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes, or procaine (e.g., Novocain) or other ester-type anesthetics (medicines that cause numbing) if you are receiving penicillin G procaine.

Diet - 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.

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.

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.

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 a penicillin, it is especially important that your health care professional know if you are taking any of the following:

  • Acetaminophen (e.g., Tylenol) (with long-term, high-dose use) or
  • Amiodarone (e.g., Cordarone) or
  • Anabolic steroids (nandrolone [e.g., Anabolin], oxandrolone [e.g., Anavar], oxymetholone [e.g., Anadrol], stanozolol [e.g., Winstrol]) or
  • Androgens (male hormones) or
  • Antithyroid agents (medicine for overactive thyroid) or
  • Carmustine (e.g., BiCNU) or
  • Chloroquine (e.g., Aralen) or
  • Dantrolene (e.g., Dantrium) or
  • Daunorubicin (e.g., Cerubidine) or
  • Disulfiram (e.g., Antabuse) or
  • Divalproex (e.g., Depakote) or
  • Estrogens (female hormones) or
  • Etretinate (e.g., Tegison) or
  • Gold salts (medicine for arthritis) or
  • Hydroxychloroquine (e.g., Plaquenil) or
  • Mercaptopurine (e.g., Purinethol) or
  • Methotrexate (e.g., Mexate) or
  • Methyldopa (e.g., Aldomet) or
  • Naltrexone (e.g., Trexan) (with long-term, high-dose use) or
  • Oral contraceptives (birth control pills) containing estrogen or
  • Other anti-infectives by mouth or by injection (medicine for infection) or
  • Phenothiazines (acetophenazine [e.g., Tindal], chlorpromazine [e.g., Thorazine], fluphenazine [e.g., Prolixin], mesoridazine [e.g., Serentil], perphenazine [e.g., Trilafon], prochlorperazine [e.g., Compazine], promazine [e.g., Sparine], promethazine [e.g., Phenergan], thioridazine [e.g., Mellaril], trifluoperazine [e.g., Stelazine], triflupromazine [e.g., Vesprin], trimeprazine [e.g., Temaril]) or
  • Plicamycin (e.g., Mithracin) or
  • Valproic acid (e.g., Depakene) - These medicines may increase the chance of liver damage if taken with cloxacillin, dicloxacillin, flucloxacillin, mezlocillin, nafcillin, oxacillin, or piperacillin
  • Amiloride (e.g., Midamor) or
  • Benazepril (e.g., Lotensin) or
  • Captopril (e.g., Capoten) or
  • Enalapril (e.g., Vasotec) or
  • Fosinopril (e.g., Monopril) or
  • Lisinopril (e.g., Prinivil, Zestril) or
  • Potassium-containing medicine or
  • Quinapril (e.g., Accupril) or
  • Ramipril (e.g., Altace) or
  • Spironolactone (e.g., Aldactone) or
  • Triamterene (e.g., Dyrenium) - Use of these medicines with penicillin G by injection may cause an increase in side effects
  • Anticoagulants (blood thinners) or
  • Dipyridamole (e.g., Persantine) or
  • Divalproex (e.g., Depakote) or
  • Heparin (e.g., Panheprin) or
  • Inflammation or pain medicine (except narcotics) or
  • Pentoxifylline (e.g., Trental) or
  • Plicamycin (e.g., Mithracin) or
  • Sulfinpyrazone (e.g., Anturane) or
  • Valproic acid (e.g., Depakene) - Use of these medicines with high doses of carbenicillin, piperacillin, or ticarcillin may increase the chance of bleeding
  • Chloramphenicol (e.g., Chloromycetin) or
  • Erythromycins (e.g., E.E.S., E-Mycin, ERYC) or
  • Sulfonamides (e.g., Gantanol, Gantrisin) or
  • Tetracyclines (e.g., Achromycin, Minocin, Vibramycin) - Use of these medicines with penicillins may prevent the penicillin from working properly
  • Cholestyramine (e.g., Questran) or
  • Colestipol (e.g., Colestid) - Use of these medicines with oral penicillin G may prevent penicillin G from working properly
  • Oral contraceptives (birth control pills) containing estrogen - Use of ampicillin, amoxicillin, or penicillin V with estrogen-containing oral contraceptives may prevent oral contraceptives from working properly, increasing the chance of pregnancy
  • Methotrexate (e.g., Mexate) - Use of methotrexate with penicillins may increase the chance of side effects of methotrexate
  • Probenecid (e.g., Benemid) - Probenecid causes penicillins to build up in the blood. This may increase the chance of side effects. However, your doctor may want to give you probenecid with a penicillin to treat some infections

Other medical problems - The presence of other medical problems may affect the use of penicillins. Make sure you tell your doctor if you have any other medical problems, especially:

  • Allergy, general (such as asthma, eczema, hay fever, hives), history of - Patients with a history of general allergies may be more likely to have a severe reaction to penicillins
  • Bleeding problems, history of - Patients with a history of bleeding problems may be more likely to have bleeding when receiving carbenicillin, piperacillin, or ticarcillin
  • Congestive heart failure (CHF) or
  • High blood pressure - Large doses of carbenicillin or ticarcillin may make these conditions worse, because these medicines contain a large amount of salt
  • Cystic fibrosis - Patients with cystic fibrosis may have an increased chance of fever and skin rash when receiving piperacillin
  • Kidney disease - Patients with kidney disease may have an increased chance of side effects
  • Mononucleosis (“mono”) - Patients with mononucleosis may have an increased chance of skin rash when receiving ampicillin, bacampicillin, or pivampicillin
  • Phenylketonuria - Some strengths of the amoxicillin chewable tablets contain aspartame, which is changed by the body to phenylalanine, a substance that is harmful to patients with phenylketonuria.
  • Stomach or intestinal disease, history of (especially colitis, including colitis caused by antibiotics) - Patients with a history of stomach or intestinal disease may be more likely to develop colitis while taking penicillins

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Penicillins: Description and Brand Names


Penicillins: Proper Use

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