Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Penicillin V. If you are concerned about side effects, discuss the risks and benefits of Penicillin V with your doctor.

The following side effects have been reported by at least 1% of people taking Penicillin V. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• black hairy tongue
• bloating
• Diarrhea
• heartburn
• nausea
• skin rash
• stomach pains
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• Fever, itchy skin, muscle pain, swollen glands, general feeling of being unwell
• numbness or weakness in the extremities
• signs of Anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don’t stop bleeding)
• signs of liver problems, e.g.:
• dark urine
• diarrhea
• loss of appetite
• nausea
• pale stools
• vomiting
• weight loss
• yellowing of the skin or whites of the eyes

Stop taking the medication and seek immediate medical attention if any of the following occur:

• diarrhea (watery and severe; may also be bloody)
• fever that appears after starting the antibiotic
• seizures
• signs of a serious allergic reaction, e.g.:
• abdominal cramps
• difficulty breathing
• nausea and vomiting
• swelling of the face and throat
• signs of a severe skin reaction, e.g.:
• a rash combined with fever or discomfort
• a rash covering a large area of the body
• a rash that spreads quickly
• blistering
• peeling

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Penicillin V.

Do not take Penicillin V if you:

• are allergic to penicillin or any ingredients of the medication
• have certain types of severe infections

There may be an interaction between penicillin and any of the following:

• BCG
• birth control pills
• chloramphenicol
• Cholera vaccine
• erythromycin
• fusidic acid
• Methotrexate
• mycophenolate
• Teriflunomide
• Tetracycline antibiotics (e.g., doxycycline, Minocycline, tetracycline)
• Tolvaptan
• typhoid vaccine
• Warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Penicillin V. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take Penicillin V.

Allergy: Some people who are allergic to cephalosporin antibiotics also experience allergic reactions to penicillin. Before you take penicillin, inform your doctor about any previous adverse reactions you have had to medications, especially cephalosporins and other penicillins. Contact your doctor at once if you experience signs of an allergic reaction, such as skin rash, itching, difficulty breathing or swelling of the face and throat.

Antibiotic-associated colitis: Penicillin V, like other antibiotics, may cause a potentially dangerous condition called antibiotic-associated, or pseudomembranous, colitis. Symptoms include severe, watery diarrhea that may be bloody. If you notice these symptoms, stop taking penicillin and contact your doctor as soon as possible.

Bacterial resistance: Misuse of an antibiotic such as penicillin may lead to the growth of resistant bacteria that will not be killed by the antibiotic. If this happens, the antibiotic may not work for you in the future. Although you may begin to feel better when you first start taking penicillin, you need to take all of the medication exactly as prescribed by your doctor to finish ridding your body of the infection and to prevent resistant bacteria from taking hold. Do not take penicillin or other antibiotics to treat a viral infection such as The Common Cold; antibiotics do not kill viruses, and using them to treat viral infections can lead to the growth of resistant bacteria.

Birth control: Whether penicillin decreases the effectiveness of birth control pills is controversial. Some doctors recommend adding another method of birth control for the rest of the menstrual cycle when penicillin is taken.

Kidney function: Penicillin is removed from the body by the kidneys. People with impaired kidney function are at risk of increased side effects and may need lower doses of penicillin. People with Kidney Disease or reduced kidney function should discuss with their doctor how Penicillin V may affect their medical condition, how their medical condition may affect the dosing and effectiveness of Penicillin V, and whether any special monitoring is needed.

Overgrowth of organisms: Prolonged treatment with penicillin may allow normal fungus or types of bacteria not killed by the antibiotic to overgrow, causing unwanted infections such as yeast infections.

Pregnancy: Usual doses of penicillin appear to be safe during pregnancy.

Breast-feeding: Penicillin V passes into breast milk. If you are a breast-