CDC Urges Providers to Reserve Scarce Penicillin for Pregnant Patients and Newborns

The Centers for Disease Control and Prevention issued urgent guidance to health-care providers on Monday, advising them that the FDA has authorized the temporary importation of an alternate penicillin formulation to address a deepening shortage of Bicillin L-A, the standard injectable treatment for syphilis. The CDC's most pressing message: preserve whatever Bicillin L-A remains for pregnant patients and infants with congenital syphilis, the only populations for whom penicillin is considered the sole acceptable treatment.

The FDA announced on March 6 that it is allowing the temporary importation of Lentocilin, a benzathine penicillin G product not ordinarily approved for use in the United States, as a substitute amid the ongoing limited availability of Bicillin L-A. The CDC's director's update, signed by Laura Hinkle Bachmann, Chief Medical Officer of the Division of STD Prevention, followed four days later.

The shortage has been compounded by a voluntary recall. King Pharmaceuticals, a Pfizer subsidiary, announced in July 2025 that it was pulling specific lots of Bicillin L-A prefilled syringes after particulates were identified during visual inspection. The affected products, covering both 1.2 million unit and 2.4 million unit formulations, had been distributed between December 11, 2023, and June 24, 2025. The supply disruption is now expected to persist through at least the third quarter of 2026.

"We recognize that jurisdictions may be affected by this recall and could experience challenges procuring enough Bicillin L-A to meet their needs," Bachmann wrote in the CDC communication. "As we await resolution of this issue, it remains critical that potentially limited inventory be used to treat the patients who need it most."

The urgency is sharpened by the scale of the syphilis crisis. Congenital syphilis rates have increased 203 percent nationwide over the past five years, according to CDC surveillance data. New Mexico, which issued its own health alert in January, ranks second in the country for congenital syphilis rates and has reported that both imported alternatives, Extencilline and Lentocilin, were temporarily unavailable to order through wholesalers as of mid-December due to supply outages. CDC guidance issued in March suggests the imported products remain available at the national level, though access has been uneven by jurisdiction.

For non-pregnant adults, providers have several alternatives. Doxycycline at 100 mg twice daily for 28 days is considered an acceptable substitute for late latent syphilis. Ceftriaxone carries limited supporting data for primary, secondary, and neurosyphilis in non-pregnant adults. Critically, other intramuscular penicillin combinations, including Bicillin C-R, are not acceptable substitutes for syphilis treatment and should not be used in that role.

The Society for Maternal and Fetal Medicine has endorsed the use of both Extencilline and Lentocilin for treating syphilis in pregnancy when Bicillin L-A is unavailable, providing professional backing for the imported alternatives in the highest-risk cases.

CDC guidance directs providers to immediately audit clinic stock for recalled lots, monitor local supply patterns to forecast need, and consider reserving remaining Bicillin L-A strictly for pregnant patients and infants. Providers are also encouraged to consider procuring Lentocilin or Extencilline for syphilis treatment in other eligible patients. In New York State, Extencilline has been added to the Medicaid reimbursable drug list, easing financial barriers for some providers.

The shortage underscores a structural vulnerability in the U.S. supply chain for a drug that has been a frontline syphilis treatment for decades, now under pressure precisely as the disease reaches its highest rates in a generation.