The U.S. is currently experiencing a shortage of amoxicillin as it enters a fall and winter season already marked by high rates of infectious illnesses.

Amoxicillin, a common antibiotic used to treat bacterial infections including pneumonia and bronchitis, is in short supply in pharmacies around the country, the Food and Drug Administration recently noted.

Three of the drug’s main manufacturers, including Hikma Pharmaceuticals, Sandoz and Teva Pharmaceuticals, reported they were facing shortages. While the driving force behind the shortage isn’t clear, a Sandoz spokeswoman told Bloomberg it’s partly due to a variety of factors.

“The combination in rapid succession of the pandemic impact and consequent demand swings, manufacturing capacity constraints, scarcity of raw materials, and the current energy crisis means we face a uniquely difficult situation,” the spokeswoman said. “We are working with key stakeholders including governments to find ways to manage this critical situation.” 

The company, she added, is trying to boost worker shifts and seek to provide alternatives to amoxicillin.

The amoxicillin shortage comes as cases of respiratory syncytial virus (RSV) in children have been skyrocketing. Recently, flu cases have also been rising earlier than expected, while the COVID-19 pandemic remains ongoing, stoking concern over a possible ‘tripledemic.’ 

While amoxicillin doesn’t treat viral diseases, it’s often given to patients to battle secondary bacterial infections, and pharmacists are concerned the shortage will exacerbate increased demand in the winter months.

Amoxicillin joins other drugs currently in short supply in the U.S., including Adderall, with the FDA recently announcing Teva was experiencing manufacturing delays.