Penicillin is an antibiotic used to treat and prevent a wide variety of bacterial infections. It works by stopping the growth of bacteria. This antibiotic treats and prevents only bacterial infections. It will not work for virus infections (such as the common cold, flu). Using any antibiotic when it is not needed can cause it to not work for future infections.
Take this medication by mouth as directed by your doctor. This medication may be taken with or without food. However, penicillin is best absorbed when taken on an empty stomach (1 hour before or 2 hours after meals). The dosage is based on your medical condition and response to treatment. For the best effect, take this antibiotic at evenly spaced times. To help you remember, take this medication at the same time(s) every day. Continue to take this medication until the full prescribed amount is finished, even if symptoms disappear after a few days. Stopping the medication too early may allow bacteria to continue to grow, which may result in a return of the infection. Tell your doctor if your condition persists or worsens.
Upset stomach, nausea, vomiting, diarrhea, and mouth sores may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Although this effect is uncommon, you may develop a black, "hairy" tongue while taking this medication. This effect is harmless and usually goes away after treatment. Maintain good oral hygiene, and brush your tongue with a soft toothbrush twice a day. Consult your doctor or pharmacist for more information. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: unusual tiredness, joint/muscle pain, easy bruising/bleeding. This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to a type of resistant bacteria. This condition may occur during treatment or weeks to months after treatment has stopped. Do not use anti-diarrhea or opioid medications if you have any of the following symptoms because these products may make them worse. Tell your doctor right away if you develop: persistent diarrhea, abdominal or stomach pain/cramping, blood/mucus in your stool. Use of this medication for prolonged or repeated periods may result in oral thrush or a new vaginal yeast infection (oral or vaginal fungal infection). Contact your doctor if you notice white patches in your mouth, a change in vaginal discharge or other new symptoms. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), new fever, severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Some products that may interact with this drug are: methotrexate, tetracyclines, khat, guar gum. Although most antibiotics are unlikely to affect hormonal birth control such as pills, patch, or ring, a few antibiotics (such as rifampin, rifabutin) can decrease their effectiveness. This could result in pregnancy. If you use hormonal birth control, ask your doctor or pharmacist for more details. Penicillin may cause false positive results with certain diabetic urine testing products (cupric sulfate-type). This drug may also affect the results of certain lab tests. Make sure laboratory personnel and your doctors know you use this drug.
If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe vomiting, persistent diarrhea.