Penicillin V

Written by Amber Watson, PharmD
Medically reviewed by Elizabeth Scheffel, PharmD
Updated on June 27, 2023

This article describes penicillin V potassium’s uses, side effects, and more. You’ll also find some coupon options to help save on the cost of penicillin V potassium.

Penicillin V potassium may cause mild or serious side effects. More common mild side effects of penicillin V potassium and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.

To learn more about penicillin V potassium’s side effects, ask your doctor or pharmacist. You can also read the prescribing information for penicillin V potassium listed in the “Article resources” section.

Mild side effects

More common mild side effects reported after taking penicillin V potassium are listed below.

This article doesn’t include all possible mild side effects of the drug. To learn more about penicillin V potassium’s side effects based on the form, refer to the prescribing information for penicillin V potassium listed in the “Article resources” section.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Mild side effects of penicillin V potassium oral tablet and oral liquid solution include:

• upper abdominal pain
• nausea or vomiting
• diarrhea
• black and “hairy” tongue
• mild allergic reaction*

* For details about this side effect, see the “Interactions and warnings for penicillin V potassium” section.

Serious side effects

Serious side effects of penicillin V potassium are listed below.

This article doesn’t include all possible serious side effects of the drug. To learn more about penicillin V potassium’s side effects based on the form, see the prescribing information for penicillin V potassium listed in the “Article resources” section.

With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.

In general, penicillin V potassium’s serious side effects include:

• severe diarrhea related to Clostridioides difficile infection
• severe allergic reaction*

* For details about this side effect, see the “Interactions and warnings for penicillin V potassium” section.

The Food and Drug Administration (FDA) approves prescription drugs such as penicillin V potassium for certain conditions. The approved use for penicillin V potassium is described below.

Use for certain bacterial infections

Doctors may prescribe penicillin V potassium for treating certain bacterial infections. Examples include scarlet fever and certain ear, skin, mouth, and respiratory infections. For this use, penicillin V potassium is usually prescribed as a short-term treatment for adults and children ages 12 years and older.

Doctors may also prescribe penicillin V potassium to help prevent certain complications related to bacterial infections. An example is rheumatic fever that’s triggered by an infection. For this use, it’s usually prescribed as a long-term treatment in adults and children ages 12 years and older.

With bacterial infections, symptoms can vary depending on the kind of infection you have. A few examples include cough, fever or chills, fatigue (low energy), and body aches.

Below you’ll find answers to a few commonly asked questions about penicillin V potassium.

Is penicillin V potassium similar to other antibiotics, such as amoxicillin?

Penicillin V potassium has some similarities to and differences from other antibiotics. Like penicillin V potassium, antibiotics are prescribed to treat certain bacterial infections. Other antibiotics may be prescribed for the same or different uses as penicillin V potassium.

For example, both penicillin V potassium and amoxicillin (Amoxil, Larotid) can be prescribed to treat ear, skin, and respiratory infections. But unlike penicillin, amoxicillin may also be prescribed to treat a certain kind of stomach infection.

If you’d like to learn more about how penicillin compares with other antibiotics, talk with your doctor or pharmacist.

What brand names are available for penicillin V potassium?

In the United States, penicillin V potassium doesn’t come in a brand-name form. The oral tablet and oral liquid solution are only available as generic medications. (A generic drug is an exact copy of the active drug in a brand-name medication.)

Can penicillin V potassium be used for a UTI?

Penicillin V potassium is not approved by the Food and Drug Administration (FDA) for treating urinary tract infections (UTIs). But if your doctor recommends it, they may still prescribe the drug off-label for this use. Off-label use is when a drug is prescribed for a condition it isn’t approved for by the FDA.

To learn more about taking penicillin V potassium for UTI, talk with your doctor.

How does penicillin V potassium work? And how long does it take to start working?

Penicillin V potassium is a type of drug called a penicillin antibiotic. It works by keeping bacteria cells from building a protective barrier around themselves. Without this barrier, the bacteria cells become weak and die.

How long it takes penicillin V potassium to start working depends on a few factors. These include the reason you’re taking the drug and the dosage your doctor prescribes.

It’s important to finish taking the course of penicillin V potassium that your doctor prescribes, even if your symptoms ease. Stopping the antibiotic early could cause the infection to return or cause the infection to become resistant to the antibiotic. This can make the infection harder to treat.

If you’d like to know more about this, talk with your doctor or pharmacist.

Below, you’ll find information about penicillin V potassium’s possible interactions and warnings.

Interactions of penicillin V potassium

Penicillin V potassium isn’t reported to interact with any medications or supplements. (Interactions can affect how a drug works.) But this doesn’t mean drug interactions with penicillin V potassium won’t happen or be reported sometime. For instance, medications created at a later time could interact with penicillin V potassium.

Because of this, you should ask your doctor and pharmacist about possible interactions with penicillin V potassium. They can check for any interactions that may affect you, such as those with:

• vaccines
• foods or alcohol
• other drugs

Warnings for penicillin V potassium

Some people should not take penicillin V potassium, and others should take it cautiously.

Penicillin V potassium could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether penicillin V potassium is a safe option for you.

Ask your doctor about specific warnings for penicillin V potassium, and be sure to tell your doctor about your:

• current health, including any allergies to medications
• past health conditions or surgeries

Allergic reaction

Penicillin V potassium can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.

If you’ve had an allergic reaction to penicillin V potassium or any of its ingredients, your doctor will likely not prescribe penicillin V potassium. They can tell you about medications that are safer options for you.

A mild allergic reaction may cause the following symptoms:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems

If you have an allergic reaction to penicillin V potassium, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

Overdose of penicillin V potassium

You should not take more penicillin V potassium than your doctor prescribes. For some drugs, doing so may lead to harmful effects or overdose.

If you think you’ve taken too much penicillin V potassium, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

Pregnancy or breastfeeding and penicillin V potassium

Information about penicillin V potassium and pregnancy and breastfeeding is described below.

Penicillin V potassium and pregnancy

In general, penicillin V potassium is considered safe to take during pregnancy. That said, ask your doctor about whether they feel it’s safe for you.

Penicillin V potassium and breastfeeding

In general, penicillin V potassium is considered safe to take while breastfeeding. That said, ask your doctor about whether they feel it’s safe for you.

This article describes penicillin V potassium’s uses, side effects, and more. Let your doctor know if you have questions about penicillin V potassium or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• Do I take any medications or supplements that may interact with penicillin V potassium?
• How do the side effects of penicillin V potassium compare with side effects of other antibiotics?
• If I’m allergic to penicillin V potassium, what other antibiotics can you prescribe to treat my condition?

• Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm
• Penicillin V. (2021). https://www.ncbi.nlm.nih.gov/books/NBK501062/
• Penicillin V potassium tablets, USP; penicillin V potassium for oral solution, USP. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/3111ca84-6f8e-45ea-91a1-9cb99c63607e/spl-doc
• Yip DW, et al. (2022). Penicillin. https://www.ncbi.nlm.nih.gov/books/NBK554560/

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.