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bicillin l-a

Bicillin L-A (Penicillin G Benzathine) is a penicillin-class antibacterial used to treat Actinomycosis, Anthrax, Botulism, Diphtheria.

Penicillin G Benzathine · by Wyeth Ayerst

⚠ FDA reports a current shortage of the injection form — availability differs between suppliers — see drug shortages →
Not yet rated· sourced from the FDA label
Rated against independent regulatory sources·Last updated June 7, 2026·How we rate
Verified againstopenFDANIH DailyMedRxClass

Key facts

Active ingredient
Penicillin G Benzathine
Form
Injectable
Strength
Penicillin G Benzathine 300,000 UNITS/ML
Type
Prescription (Rx)
Brand or generic
Brand-name
May treat
actinomycosis, anthrax, botulism
Manufacturer
Wyeth Ayerst
FDA application
NDA050131
Availability
Discontinued (per FDA)

What is Bicillin L-A?

From the FDA label:Bicillin L-A (penicillin G benzathine injectable suspension) is available for deep intramuscular injection. Penicillin G benzathine is prepared by the reaction of dibenzylethylene diamine with two molecules of penicillin G. It is chemically designated as (2 S , 5 R , 6 R )-3,3-Dimethyl-7-oxo-6-(2-phenylacetamido)-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid compound with N,N' - dibenzylethylenediamine (2:1), tetrahydrate. It occurs as a white, crystalline powder and is very slightly soluble in water and sparingly soluble in alcohol. Its chemical structure is as follows: Bicillin L-A contains penicillin G benzathine in aqueous suspension with sodium citrate buffer and, as w/v, approximately 0.65% sodium citrate, 0.59% povidone, 0.54% carboxymethylcellulose sodium, 0.53% lecithin, 0.12% methylparaben, and 0.013% propylparaben. Bicillin L-A contains approximately 0.11 mEq of sodium per 600,000 units of penicillin G (approximately 2.59 mg of sodium per 600,000 units of penicillin G). Bicillin L-A suspension in the disposable-syringe formulation is viscous and opaque. It is available in a 1 mL, 2 mL, and 4 mL sizes containing the equivalent of 600,000 (actual volume of 1.17 mL contains 620,100), 1,200,000 (actual volume of 2.34 mL contains 1,240,200), and 2,400,000 (actual volume of 4.67 mL contains 2,475,100) units respectively of penicillin G as the benzathine salt. Read…

How to use

Streptococcal (Group A) Upper Respiratory Infections (for example, pharyngitis) Adults—a single injection of 1,200,000 units; older pediatric patients—a single injection of 900,000 units; infants and pediatric patients under 60 lbs.—300,000 to 600,000 units. Syphilis Primary, secondary, and latent—2,400,000 units (1 dose). Late (tertiary and neurosyphilis)—2,400,000 units at 7-day intervals for three doses. Congenital—under 2 years of age: 50,000 units/kg/body weight; ages 2 to 12 years: adjust dosage based on adult dosage schedule. Yaws, Bejel, and Pinta —1,200,000 units (1 injection). Prophylaxis —for rheumatic fever and glomerulonephritis. Following an acute attack, penicillin G benzathine (parenteral) may be given in doses of 1,200,000 units once a month or 600,000 units every 2 weeks. METHOD OF ADMINISTRATION BICILLIN L-A IS INTENDED FOR INTRAMUSCULAR INJECTION ONLY. DO NOT INJECT INTO OR NEAR AN ARTERY OR NERVE, OR INTRAVENOUSLY OR ADMIX WITH OTHER INTRAVENOUS SOLUTIONS. (SEE WARNINGS SECTION.) Administer by DEEP INTRAMUSCULAR INJECTION in the upper, outer quadrant of the buttock (dorsogluteal) or the ventrogluteal site. In neonates, infants and small children, the midlateral aspect of the thigh may be preferable. Administration in the anterolateral thigh is not recommended due to the adverse effects observed (see WARNINGS section), and vascularity of this region. When…

Side effects

As with other penicillins, untoward reactions of the sensitivity phenomena are likely to occur, particularly in individuals who have previously demonstrated hypersensitivity to penicillins or in those with a history of allergy, asthma, hay fever, or urticaria. As with other treatments for syphilis, the Jarisch-Herxheimer reaction has been reported. The following adverse reactions have been reported with Bicillin L-A during post-marketing experience: Skin and Appendages: Stevens-Johnson syndrome (SJS) and drug reaction with eosinophilia and systemic symptoms (DRESS). (See WARNINGS .) Immune System Disorders: Acute myocardial ischemia with or without myocardial infarction occurring as part of an allergic reaction. The following have been reported with parenteral penicillin G (the active moiety in Bicillin L-A): General: Hypersensitivity reactions including the following: skin eruptions (maculopapular to exfoliative dermatitis), urticaria, laryngeal edema, fever, eosinophilia; other serum sickness-like reactions (including chills, fever, edema, arthralgia, and prostration); and anaphylaxis including shock and death: severe cutaneous adverse reactions (SCAR), such as toxic epidermal necrolysis (TEN) and acute generalized exanthematous pustulosis (AGEP). (See WARNINGS .) Note: Urticaria, other skin rashes, and serum sickness-like reactions may be controlled with antihistamines and,…

FDA Boxed Warning (the FDA’s most serious warning)

Boxed (black-box) warning — from the FDA label

Prior to administration of this drug, carefully read the WARNINGS , ADVERSE REACTIONS , and DOSAGE AND ADMINISTRATION sections of the labeling. WARNING NOT FOR INTRAVENOUS USE. DO NOT INJECT INTRAVENOUSLY OR ADMIX WITH OTHER INTRAVENOUS SOLUTIONS. THERE HAVE BEEN REPORTS OF INADVERTENT INTRAVENOUS ADMINISTRATION OF PENICILLIN G BENZATHINE WHICH HAS BEEN ASSOCIATED WITH CARDIORESPIRATORY ARREST AND DEATH. Prior to administration of this drug, carefully read the WARNINGS , ADVERSE REACTIONS , and DOSAGE AND ADMINISTRATION sections of the labeling.

Warnings

Important safety information

Prior to administration of this drug, carefully read the WARNINGS , ADVERSE REACTIONS , and DOSAGE AND ADMINISTRATION sections of the labeling. Penicillin G benzathine should only be prescribed for the indications listed in this insert. Anaphylaxis SERIOUS AND OCCASIONALLY FATAL HYPERSENSITIVITY (ANAPHYLACTIC) REACTIONS HAVE BEEN REPORTED IN PATIENTS ON PENICILLIN THERAPY. THESE REACTIONS ARE MORE LIKELY TO OCCUR IN INDIVIDUALS WITH A HISTORY OF PENICILLIN HYPERSENSITIVITY AND/OR A HISTORY OF SENSITIVITY TO MULTIPLE ALLERGENS. THERE HAVE BEEN REPORTS OF INDIVIDUALS WITH A HISTORY OF PENICILLIN HYPERSENSITIVITY WHO HAVE EXPERIENCED SEVERE REACTIONS WHEN TREATED WITH CEPHALOSPORINS. BEFORE INITIATING THERAPY WITH BICILLIN L-A, CAREFUL INQUIRY SHOULD BE MADE CONCERNING PREVIOUS HYPERSENSITIVITY REACTIONS TO PENICILLINS, CEPHALOSPORINS, OR OTHER ALLERGENS. IF AN ALLERGIC REACTION OCCURS, BICILLIN L-A SHOULD BE DISCONTINUED AND APPROPRIATE THERAPY INSTITUTED. SERIOUS ANAPHYLACTIC REACTIONS REQUIRE IMMEDIATE EMERGENCY TREATMENT WITH EPINEPHRINE. OXYGEN, INTRAVENOUS STEROIDS AND AIRWAY MANAGEMENT, INCLUDING INTUBATION, SHOULD ALSO BE ADMINISTERED AS INDICATED. Severe cutaneous adverse reactions Severe cutaneous adverse reactions (SCAR), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP) have been reported in patients taking penicillin G (the active moiety in Bicillin L-A). When SCAR is suspected, Bicillin L-A should be discontinued immediately and an alternative treatment should be considered. Clostridioides difficile associated diarrhea Clostridioides difficile associated-diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including Bicillin L-A, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile . C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibacterial use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile , and surgical evaluation should be instituted as clinically indicated. Method of Administration Do not inject into or near an artery or nerve. See administration instructions below. Injection into or near a nerve may result in permanent neurological damage. Inadvertent intravascular administration, including inadvertent direct intra-arterial injection or injection immediately adjacent to arteries, of Bicillin L-A and other penicillin preparations has resulted in severe neurovascular damage, including transverse myelitis with permanent paralysis, gangrene requiring amputation of digits and more proximal portions of extremities, and necrosis and sloughing at and surrounding the injection site consistent with the diagnosis of Nicolau syndrome. Such severe effects have been reported following injections into the buttock, thigh, and deltoid areas. Other serious complications of suspected intravascular administration which have been reported include immediate pallor, mottling, or cyanosis of the extremity both distal and proximal to the injection site, followed by bleb formation; severe edema requiring anterior and/or posterior compartment fasciotomy in the lower extremity. The above-described severe effects and complications have most often occurred in infants and small children. Prompt consultation with an appropriate specialist is indicated if any evidence of compromise of the blood supply occurs at, proximal to, or distal to the site of injection. 1–9 (See PRECAUTIONS , and DOSAGE AND ADMINISTRATION sections.) FOR DEEP INTRAMUSCULAR INJECTION ONLY. There have been reports of inadvertent intravenous administration of penicillin G benzathine which has been associated with cardiorespiratory arrest and death. Therefore, do not inject intravenously or admix with other intravenous solutions. (See DOSAGE AND ADMINISTRATION section.) Administer by DEEP INTRAMUSCULAR INJECTION ONLY in the upper, outer quadrant of the buttock (dorsogluteal) or the ventrogluteal site. Quadriceps femoris fibrosis and atrophy have been reported following repeated intramuscular injections of penicillin preparations into the anterolateral thigh. Because of these adverse effects and the vascularity of this region, administration in the anterolateral thigh is not recommended.

Who should not take Bicillin L-A

A history of a previous hypersensitivity reaction to any of the penicillins is a contraindication.

Overdose — what happens if you take too much

Penicillin in overdosage has the potential to cause neuromuscular hyperirritability or convulsive seizures.

U.S. Poison Control: call or text 1-800-222-1222 (free, 24/7). In an emergency call 911. From the FDA label; not medical advice.

Interactions

Tetracycline, a bacteriostatic antibiotic, may antagonize the bactericidal effect of penicillin, and concurrent use of these drugs should be avoided. Concurrent administration of penicillin and probenecid increases and prolongs serum penicillin levels by decreasing the apparent volume of distribution and slowing the rate of excretion by competitively inhibiting renal tubular secretion of penicillin.

Drug class

May treat (source: NIH RxClass)

See how Bicillin L-A ranks — best-rated penicillin-class antibacterial for:

Dosage forms

Injectable

The forms currently marketed in the U.S., per the FDA National Drug Code Directory.

Ways to save

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Frequently asked questions

What does Bicillin L-A treat?
Bicillin L-A (Penicillin G Benzathine) may be used to treat actinomycosis, anthrax, botulism, diphtheria, empyema, endocarditis, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.
Is there a coupon or discount for Bicillin L-A?
pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Bicillin L-A. To pay less, ask your prescriber or pharmacist whether a generic equivalent exists, check the manufacturer's copay/savings card and patient-assistance program, and compare a pharmacy discount card against your insurance copay. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.
Who makes Bicillin L-A?
Bicillin L-A is marketed by Wyeth Ayerst. You can see Wyeth Ayerst's full profile, rating, and other products on pharmaranks.
Is Bicillin L-A a brand-name or generic drug?
Bicillin L-A is a brand-name product with the active ingredient Penicillin G Benzathine.
Is Bicillin L-A available over the counter?
No. Bicillin L-A is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.
What forms does Bicillin L-A come in?
Bicillin L-A is currently marketed as injectable, per the FDA's National Drug Code Directory.
What class of drug is Bicillin L-A?
Bicillin L-A is classified as penicillin-class antibacterial, per the FDA's Established Pharmacologic Class.
Is Bicillin L-A FDA-registered?
Bicillin L-A is on record with the U.S. FDA under application number NDA050131. You can verify this on its official FDA label.
Is Bicillin L-A safe?
There's no single safe-or-not verdict, and we don't yet have a composite recall-safety score for Bicillin L-A. Review its FDA-label side effects and warnings below, and always consult a licensed professional.
What are the side effects of Bicillin L-A?
Bicillin L-A's side effects are taken directly from its FDA label. From the label: As with other penicillins, untoward reactions of the sensitivity phenomena are likely to occur, particularly in individuals who have previously demonstrated hypersensitivity to penicillins or in those with a history of allergy, asthma, hay fever, or urticaria. As with other treatments for syphilis,… Both common and serious reactions are documented in full on this page. This is general reference from the FDA, not medical advice — always consult a professional.

Clinical content sourced from the FDA label via openFDA (U.S. FDA). View the FDA label on DailyMed → Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.

What people report to the FDA about PENICILLIN G BENZATHINE

The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 512 reports naming PENICILLIN G BENZATHINE — the active ingredient in Bicillin L-A, and the FDA flagged 72% 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 hypersensitivity114 reports
  • embolia cutis medicamentosa33 reports
  • hypersensitivity31 reports
  • acute kidney injury30 reports
  • rash22 reports
  • diarrhoea19 reports
  • foetal exposure during pregnancy19 reports
  • jarisch-herxheimer reaction18 reports

Read these as a signal, not a rate. A report does not mean PENICILLIN G BENZATHINE 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.

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

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