A baby formula shortage in the United States is driving parents to swap, sell and offer leftover supplies to each other, while President Joe Biden spoke with manufacturers and retailers Thursday about the plight facing families.

The president discussed with executives from Mead Johnson and Gerber how they could increase production and how his administration could help, and talked with leaders from Walmart and Target about how to restock shelves and address regional disparities in access to formula, according to the White House.

The administration plans to monitor possible price gouging and work with trading partners in Mexico, Chile, Ireland, and the Netherlands on imports, even though 98% of baby formula is domestically made.

The problem is the result of supply chain disruptions and a safety recall, and has had a cascade of effects: Retailers are limiting what customers can buy, and doctors and health workers are urging parents to contact food banks or physicians’ offices, in addition to warning against watering down formula to stretch supplies or using online DIY recipes.

The shortage is weighing particularly on lower-income families after the recall by formula maker Abbott stemming from contamination concerns. That recall wiped out many brands covered by WIC, a federal program like food stamps that serves mothers, infants and children, though the program now permits brand substitutes. The Biden administration is working with states to make it easier for WIC recipients to buy different sizes of formula that their benefits might not currently cover.

Parents, particularly moms, are using social media to bridge the supply gaps.

Ashley Maddox, a 31-year-old mother of two from San Diego, started a Facebook group on Wednesday after failing to find formula for her 5-month-old son, Cole, at the commissary on the Navy base.

“I connected with a gal in my group and she had seven cans of the formula I need that were just sitting in her house that her baby didn’t need anymore,” she said. “So I drove out, it was about a 20-minute drive and picked it up and paid her. It was a miracle.”

She said there was already a stigma attached to being a non-breastfeeding mom and that the group has become supportive. “To not be able to have that formula, it’s scary,” she said.

Jennifer Kersey, 36 of Cheshire, Connecticut, said she was down to her last can of formula for her 7-month old son, Blake Kersey Jr., before someone saw her post on a Facebook group and came by with a few sample cans.

“At first I was starting to panic,” she said. “But, I’m a believer in the Lord, so I said, ’God, I know you’re going to provide for me and I just started reaching out to people, ‘Hey do you have this formula?’

She said she and others in the group are helping each other, finding stores which may have the formula in stock and getting formula to mothers who need it.

Kimberly Anderson, 34, of Hartford County, Maryland, said her 7 1/2-month-old son takes a prescription formula that has been nearly impossible to find locally. She turned to social media and said people in Utah and Boston found the formula, which she paid to have shipped.

“They say it takes a village to raise a baby,” she said. “Little did I know my village spans the entire U.S. as I ping friends/family for their zip codes so I can check their local Walmarts to have them ship directly to me.”

Erika Thompson, 28, a mother of three in Wallingford, Connecticut said it’s become almost a full-time job for her to track down the hypoallergenic formula her 3 1/2-month-old daughter, Everly, must have. She said friends out of state have also been looking for her and shipping cans if they find them. She is down to one small sample can, which she said might last a couple more days.

“You can travel everywhere — countless towns, stores, Amazon, online,” she said. “Honestly, it’s heartbreaking.”

She said she was unable to produce an adequate supply of milk, but she should not have to explain that to people. “It’s not our fault,” she said.

Shortages of basic goods have been a problem since the start of the coronavirus pandemic in early 2020. Access to medical supplies, computer chips, household appliances, autos and other goods has been hurt by closed factories and outbreaks of the virus, as well as storms and other climate-related events.

A safety recall compounded the challenges regarding baby formula.

The Food and Drug Administration warned consumers on Feb. 17 to avoid some powdered baby formula products from a Sturgis, Michigan, facility run by Abbott Nutrition, which then initiated a voluntary recall. According to findings released in March by federal safety inspectors, Abbott failed to maintain sanitary conditions and procedures at the plant.

The FDA launched its investigation after four babies became sick with a rare bacterial infection after consuming formula manufactured at the plant. All four had to be hospitalized and two died. Chicago-based Abbott said in a statement “there is no evidence to link our formulas to these infant illnesses.” Samples of the bacteria collected from the infants did not match those found in the company’s factory, Abbott noted.

Abbott said that pending FDA approval, “we could restart the site within two weeks.” The company would begin by first producing EleCare, Alimentum and metabolic formulas and then start production of Similac and other formulas. Once production began, it would take six weeks to eight weeks for the baby formula to be available on shelves.

On Tuesday, the FDA said it was working with U.S. manufacturers to increase their output and streamlining paperwork to allow more imports. The agency noted that supply chain issues associated with the pandemic were part of the problem and that consumers bought more baby formula in April than in the month before the recall.