Drug information

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Pronounce:
Penicillin G (Potassium or Sodium)
Other Names
Pfizerpen, penicillin G potassium, penicillin G sodium, penicillin G aqueous, aqueous crystalline penicillin G, benzylpenicillin
Drug Class
Antibacterial (Penicillin)

What is penicillin G (potassium or sodium)? What is penicillin G (potassium or sodium)?

What is penicillin G (potassium or sodium)?

Penicillin G (potassium or sodium) is an antibacterial prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of certain serious bacterial infections, such as pneumonia, meningitis, gonorrhea, syphilis, and others.

Pneumonia and syphilis can be opportunistic infections (OI) of HIV. An OI is an infection that occurs more frequently or is more severe in people with weakened immune systems—such as people with HIV—than in people with healthy immune systems. To learn more about OIs, read the HIVinfo What is an Opportunistic Infection? fact sheet.

How is penicillin G (potassium or sodium) used in people with HIV? How is penicillin G (potassium or sodium) used in people with HIV?

How is penicillin G (potassium or sodium) used in people with HIV?

The Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents With HIV and/or the Guidelines for the Prevention and Treatment of Opportunistic Infections in Children With and Exposed to HIV include recommendations on the use of penicillin G (potassium or sodium) in people with HIV to treat community acquired pneumonia and syphilis.

The recommended uses may not always be consistent with FDA-approved uses of penicillin G (potassium or sodium). See the Adult and Pediatric Opportunistic Infection Guidelines for complete information on recommended uses of penicillin G (potassium or sodium) in adults and children with HIV. Penicillin G (potassium or sodium) may have other recommended uses not listed above.

What should I tell my health care provider before using penicillin G (potassium or sodium)? What should I tell my health care provider before using penicillin G (potassium or sodium)?

What should I tell my health care provider before using penicillin G (potassium or sodium)?

Before using penicillin G (potassium or sodium), tell your health care provider:

  • If you are allergic to penicillin G (potassium or sodium), penicillin- or cephalosporin-class antibiotics, or any other medicines.
  • About any medical conditions you have or have had, including asthma, allergies, kidney problems, or electrolyte imbalances.
  • If you are on a sodium- or potassium-restricted diet.
  • About any health conditions that may prevent you from receiving medicine by injection.
  • If you are pregnant or plan to become pregnant. Talk to your health care provider about the risks and benefits of using penicillin G (potassium or sodium) during pregnancy. The Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents With HIV may include other recommendations on the use of penicillin G (potassium or sodium) during pregnancy. Please refer to these guidelines for additional information.
  • If you are breastfeeding or plan to breastfeed. For mothers with HIV in the United States, the Guideline recommends speaking with your health care provider to discuss options for feeding your baby. Mothers with suppressed viral load have a less than 1% chance of transmitting HIV to their baby via their own milk. Although most medicines are safe to use while breastfeeding, some medicines should be avoided. Always let your health care provider know about all the medicines and supplements you are using before you start breastfeeding.
  • About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Penicillin G (potassium or sodium) may affect the way other medicines or products work, and other medicines or products may affect how penicillin G (potassium or sodium) works. Ask your health care provider if there are interactions between penicillin G (potassium or sodium) and the other medicines you take.

How should I use penicillin G (potassium or sodium)? How should I use penicillin G (potassium or sodium)?

How should I use penicillin G (potassium or sodium)?

Penicillin G (potassium or sodium) is usually given by intravenous infusion or intramuscular injection, but it may also be given by other routes. It may be administered by a health care provider in a hospital or clinic. Some people may use penicillin G (potassium or sodium) at home. If you use penicillin G (potassium or sodium) at home, your health care provider will teach you how to use the medicine. It is important that you use penicillin G (potassium or sodium) exactly as your health care provider has instructed. If you do not understand how to use penicillin G (potassium or sodium), ask your health care provider.

It is important to complete the full prescribed course of treatment with penicillin G (potassium or sodium), even if you begin to feel better. If you stop using penicillin G (potassium or sodium) too soon or skip doses, your infection may not be fully treated, and the bacteria may become harder to treat (resistant).

What side effects can penicillin G (potassium or sodium) cause? What side effects can penicillin G (potassium or sodium) cause?

What side effects can penicillin G (potassium or sodium) cause?

Penicillin G (potassium or sodium) may cause side effects that can be mild or serious. To learn about possible side effects of penicillin G (potassium or sodium), see the FDA drug labels for penicillin G potassium injection (powder, for solution) and penicillin G sodium injection (powder, for solution) or talk to your health care provider or pharmacist. Tell your health care professional if you have any side effect that bothers you or that does not go away. Your health care professional may be able to tell you about ways to prevent or reduce some side effects.

You may report side effects to FDA at 1-800-FDA-1088 (1-800-332-1088) or online.

How should penicillin G (potassium or sodium) be stored? How should penicillin G (potassium or sodium) be stored?

How should penicillin G (potassium or sodium) be stored?

  • Store vials of penicillin G (potassium) dry powder below 86°F (30°C). Once the powder in the vial has been reconstituted, the sterile solution is stable in a refrigerator for 1 week.
  • Store vials of penicillin G (sodium) dry powder at room temperature, 68°F to 77°F (20°C to 25°C). Once the powder in the vial has been reconstituted, the sterile solution may be kept in a refrigerator, between 36°F to 46°F (2°C to 8°C), for 3 days.
  • Do not use penicillin G (potassium or sodium) if the original seal over the container opening is broken or missing.
  • Throw away penicillin G (potassium or sodium) that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine. For information on disposing of needles and other sharps, please refer to these guidelines or ask your health care provider or pharmacist.
  • Keep penicillin G (potassium or sodium) and all medicines out of reach of children.

Where can I find more information about penicillin G (potassium or sodium)? Where can I find more information about penicillin G (potassium or sodium)?

Where can I find more information about penicillin G (potassium or sodium)?

Last Reviewed: July 14, 2025