(KTLA) — CVS and Walgreens are among the retailers limiting sales of baby formula amid the ongoing nationwide shortage. Citing challenges with supply, both chains are capping purchases to three baby formula products per transaction.

Parents around the U.S. hoping to buy baby formula are being met with empty shelves due to the shortage, which only got worse in February when a major baby food manufacturer, Abbott Nutrition, recalled powdered baby formula products manufactured at a Michigan plant.

The recall, which affected the Similac, Alimentum, and EleCare brands, was issued after four babies were hospitalized with bacterial infections, and two died after taking powdered baby formula, according to the U.S. Food and Drug Administration.

The recall exacerbated already existing baby formula supply issues caused by pandemic-snarled supply chains and shortages of ingredients. Now, companies are limiting how much baby formula customers can buy at once.

“Following supplier challenges and increased customer demand, we currently have a limit of three baby formula products per purchase in our stores and online,” CVS spokesperson Monica Prinzing said in a statement. “We’re continuing to work with our baby formula vendors to address this issue and we regret any inconvenience this causes our customers.”

Similarly, a Walgreens spokesperson pointed to the same supply issue, saying the chain is placing limits to help improve inventory. “Due to increased demand and various supplier challenges, infant and toddler formulas are seeing constraint across the country. Similar to other retailers, we put into effect purchase limits of three per transaction on all infant and toddler formula to help improve inventory,” spokesperson Kris Lathan told NEWS10’s sister station in Los Angeles. “We continue to work diligently with our supplier partners to best meet customer demands.”

As of April 13, about 31% of formula products were out of stock across the country, according to retail software company Datasembly. Target and Kroger started rationing online formula purchases that month, the Wall Street Journal reported.

In a statement issued last month, Abbott Nutrition representatives said they were aware that their recall “caused additional stress and anxiety in an already challenging situation of a global supply shortage.” The company said it was producing more Similac Advance powder formula for U.S. babies at its plant in Ireland, and prioritizing formula production at its Ohio plant to help replenish the supply in the market. 

In the meantime, federal authorities are warning parents and caregivers against diluting infant formula or giving homemade formula to infants. Americans were also asked to avoid buying imported formula online, since it can be counterfeit, FDA officials said.