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Blood plasma is big business along the U.S.–Mexico border and it runs through a legal and ethical gray zone.
On a chilly, overcast Saturday in Laredo, Texas, a steady flow of Mexican citizens walks across the international bridge into the United States. Many are headed to shop or visit relatives. Others, like Angel Hernández from Nuevo Laredo, are making the crossing for another reason: to sell their blood plasma.
“Here they give us financial support, and that helps,” Hernández said in Spanish after leaving the Grifols Plasma Center a few blocks from the bridge. On this trip, he earned $120 — a significant sum once converted to pesos.
He said he makes the walk twice a week, just to donate.
So does José García, also from Nuevo Laredo. He estimates that “a lot of people from Mexico do this.”
He had just finished donating; a blue bandage on his elbow covered the spot where the needle had been. He said he feels fine as long as he eats, sleeps and hydrates well.
These donors are part of a cross-border system that has become vital to the global supply of plasma-based medicines. The United States is home to the vast majority of the world’s plasma collection centers and provides roughly 70% of the plasma used to manufacture therapies for patients worldwide.
Plasma — the pale, straw-colored component of blood — is processed into therapies that treat immune deficiencies, bleeding disorders and other serious conditions. For patients who depend on those drugs, every donation matters.
Supporters of the system argue that paying donors is both fair and essential. Peter Martin Jaworski, a professor at Georgetown University who studies the plasma industry, notes that those Mexican donors are helping patients far beyond the border.
“One out of every ten liters is coming from a Mexican who crosses the border into the United States,” he said. “That’s an enormous amount of benefit to patients in the U.S. that is given by people from Mexico.”
In the United States, plasma donors are allowed to be tapped up to twice a week, or 104 times a year — one of the highest permitted frequencies in the world. Studies of the industry suggest donors commonly earn between about $30 and $70 per session, though some centers and promotions pay more.
For people living paycheck to paycheck on both sides of the border, that money can act as a financial pressure valve — a way to cover rent, utilities or groceries when nothing else is available.
But the cross-border plasma trade exists in a murky corner of U.S. immigration law.
Mexican citizens who live near the border can obtain a special document known as a border-crossing card, or BCC, which lets them enter nearby U.S. cities for short trips. Under U.S. rules, people using visitor visas or BCCs are not allowed to work in the United States.
On paper, plasma donation is not considered “work.” Plasma companies describe the money donors receive as a “token of appreciation” or a gift for their time, not as wages. Legally, it is treated as compensation for a biological product rather than as a paycheck for labor.
That distinction became a flash point in 2021. That year, U.S. Customs and Border Protection (CBP) abruptly decided that giving plasma for money did count as work and began turning away Mexican nationals who tried to cross on short-term visas to donate. Plasma companies, including Grifols and CSL Plasma, sued CBP, arguing that the agency had overstepped its authority and jeopardized the supply of lifesaving medicines.
In September 2022, a federal district judge in Washington, D.C., issued a preliminary injunction, ordering immigration officials to once again allow Mexican citizens with B1/B2 visas and border-crossing cards to sell their plasma in the United States while the case proceeds.
As a result, border plasma centers have reopened their doors to short-term visitors. But the underlying uncertainty remains: Are these donors working in the U.S., or simply receiving gifts for their time?
Journalist Kathleen McLaughlin, author of "Blood Money: The Story of Life, Death, and Profit Inside America’s Blood Industry," argues that the system depends on a “carefully constructed legal fiction.”
When a Mexican citizen crosses the bridge using their border-crossing card, they’re not supposed to come over to work, she has said. But they’re going to be paid for their plasma. So, is that a violation of their visa?
For now, the answer from U.S. authorities is effectively “no” — at least as long as the injunction stands and the payments are treated as something other than wages.
McLaughlin and other critics say this has produced a “don’t ask, don’t tell” culture at the border. Donors she has interviewed say they’re advised not to tell U.S. officials that they’re crossing to sell plasma, even though the practice is widely understood in border communities.
Many remove their tell-tale blue bandages before walking back over the bridge into Mexico, hoping to avoid extra questions.
“No one really wants to look at it too closely,” McLaughlin said. “Donors don’t, because they need the money. Companies don’t, because they need the plasma. And governments don’t, because shutting it down could create a public-health crisis.”
As long as that system holds, thousands of Mexicans will keep lining up at border crossings, selling their plasma to sustain an international industry and the patients around the world who rely on it.
