Penicillin G: uses, dosing, side effects & brands

Penicillin G is a penicillin-class antibacterial sold in the U.S. under 2 brand and generic names, for actinomycosis, anthrax and botulism. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.

By the pharmaranks editorial teamReviewed against the FDA (openFDA label, NDC Directory & Enforcement) sourcesUpdated Jul 24, 2026How we research

Key facts

Drug class: Penicillin-Class Antibacterial
Treats (across its forms): Actinomycosis, Anthrax and Botulism
Available as: Injectable · Solution
Sold as: 2 products — Penicillin G Sodium and Penicillin G Potassium
Prescription?: Prescription only
Generic available?: Yes

How penicillin g is dosed

From the FDA label for Penicillin G Potassium (application ANDA060306). Other penicillin g products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.

Penicillin G Potassium for Injection, USP may be given intravenously or intramuscularly. The usual dose recommendations are as follows: Adult Patients (*)Because of its short half-life, Penicillin G is administered in divided doses, usually every 4-6 hours with the exception of meningococcal meningitis/septicemia, i.e., every 2 hours. Pediatric Patients This product should not be administered to patients requiring less than one million units per dose. (see PRECAUTIONS, Pediatric Use) Renal Impairment Penicillin G is relatively nontoxic, and dosage adjustments are generally required only in cases of severe renal impairment. The recommended dosage regimens are as follows: Creatinine clearance less than 10 mL/min/1.73 m2; administer a full loading dose (see recommended dosages in the tables above) followed by one-half of the loading dose every 8 to 10 hours. Uremic patients with a creatinine clearance greater than 10 mL/min/1.73 m2; administer a full loading dose (see recommended dosages in the tables above) followed by one-half of the loading dose every 4 to 5 hours. Additional dosage modifications should be made in patients with hepatic disease and renal impairment. For most acute infections, treatment should be continued for at least 48 to 72 hours after the patient becomes asymptomatic. Antibiotic therapy for Group A β-hemolytic streptococcal infections should be maintained…

Penicillin G side effects

Body as a whole The Jarisch-Herxheimer reaction is a systemic reaction, that may occur after the initiation of penicillin therapy in patients with syphilis or other spirochetal infections (i.e., Lyme disease and Relapsing fever). The reaction begins one to two hours after initiation of therapy and disappears within 12 to 24 hours. It is characterized by fever, chills, myalgias, headache, exacerbation of cutaneous lesions, tachycardia, hyperventilation, vasodilation with flushing and mild hypotension. The pathogenesis of the Herxheimer reaction may be due to the release from the spirochetes of heat-stable pyrogen. Hypersensitivity reactions The reported incidence of allergic reactions to all penicillins ranges from 0.7 to 10 percent in different studies (see WARNINGS). Sensitization is usually the result of previous treatment with a penicillin, but some individuals have had immediate reactions when first treated. In such cases, it is postulated that prior exposure to penicillin may have occurred via trace amounts present in milk or vaccines. Two types of allergic reactions to penicillin are noted clinically – immediate and delayed. Immediate reactions usually occur within 20 minutes of administration and range in severity from urticaria and pruritus to angioneurotic edema, laryngospasm, bronchospasm, hypotension, vascular collapse and death (see WARNINGS). Such immediate…

Who shouldn’t take penicillin g

A history of a hypersensitivity (anaphylactic) reaction to any penicillin is a contraindication.

Every penicillin g product we track (2)

Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.

Penicillin G products
#	Drug	Rating	Type	Form	Generic?	Pharmacy pays
1	Penicillin G Sodium	72/100	Prescription	Injectable	No data	—	View →
2	Penicillin G Potassium	56/100	Prescription	Injectable	No data	—	View →

Combination products containing penicillin g

A combination is a different drug — different dosing, different warnings. It is listed here so you can find it, not so you can substitute it.

Penicillin G recalls

From the FDA Enforcement database. A recall covers specific lots — not the drug as a whole.

How long penicillin g keeps

The date on a sealed pack is not the only one: some penicillin g labels start a second clock once the product is opened or mixed, as short as 7 days.

Does penicillin g expire? The in-use limits and storage rules from its labels

Penicillin G and breastfeeding

From LactMed, the US National Library of Medicine’s Drugs and Lactation Database — quoted, not rewritten.

Limited information indicates that penicillin G produces low levels in milk that are not expected to cause adverse effects in breastfed infants. Occasionally disruption of the infant's gastrointestinal flora, resulting in diarrhea or thrush have been reported with penicillins, but these effects have not been adequately evaluated. Penicillin G is acceptable in nursing mothers.

Full LactMed record for penicillin g: levels in milk, effects in breastfed infants, and the drugs it would consider instead

National Institute of Child Health and Human Development, record revised July 15, 2024. LactMed states its information is not a substitute for professional judgement.

What people report to the FDA about penicillin g

The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 1,178 reports naming penicillin g, and the FDA flagged 32% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:

drug hypersensitivity543 reports
hypersensitivity285 reports
rash95 reports
dyspnoea81 reports
drug intolerance64 reports
nausea55 reports
headache49 reports
anaphylactic reaction48 reports

Read these as a signal, not a rate. A report does not mean penicillin g caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.

Source: openFDA drug/event (FAERS), retrieved August 25, 2026.

Related calculators

How long it stays in your system →

Frequently asked questions

What is penicillin g?

Penicillin G Potassium is a penicillin-class antibacterial used to treat Actinomycosis, Anthrax, Botulism, Diphtheria.

What kind of drug is penicillin g?

The FDA classifies penicillin g as a penicillin-class antibacterial. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.

Can you take penicillin g with other medicines?

It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run penicillin g against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.

What brand names is penicillin g sold under?

We track 2 penicillin g-containing products in the U.S.: Penicillin G Sodium and Penicillin G Potassium. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.

What forms does penicillin g come in?

Across the brands we track, penicillin g is currently marketed as injectable and solution, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.

Is there a generic penicillin g?

Yes. Our catalog lists 2 generic penicillin g products alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.

Has penicillin g been recalled?

The FDA's Enforcement database lists 3 recall records whose product description mentions penicillin g. The most recent: Bicillin L-A (penicillin G benzathine injectable suspension) (Jul 10, 2025). A recall applies to specific lots, not to the drug as a whole — check the record for the affected lot numbers.

Cite this page

APA: pharmaranks. (2026, July 24). Penicillin G: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/penicillin-g
MLA: “Penicillin G: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/penicillin-g.

We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.

Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.

Read the full FDA label for penicillin g on DailyMed (NIH) ↗.