Amid a national shortage of a critical medicine, US hospitals are hoarding vials, delaying surgeries, and turning away patients, The New York Times reports. The medicine in short supply: solutions of sodium bicarbonate—aka, baking soda.

The simple drug is used in all sorts of treatments, from chemotherapies to those for organ failure. It can help correct the pH of blood and ease the pain of stitches. It is used in open-heart surgery, can help reverse poisonings, and is kept on emergency crash carts. But, however basic and life-saving, the drug has been in short supply since around February.

The country’s two suppliers, Pfizer and Amphastar, ran low following an issue with one of Pfizer’s suppliers—the issue was undisclosed due to confidentiality agreements. Amphastar’s supplies took a hit with a spike in demand from desperate Pfizer customers. Both companies told the NYT that they don’t know when exactly supplies will be restored. They speculate that it will be no earlier than June or August.

As hospitals and pharmacists struggle with the sodium bicarbonate shortage, experts note that it’s just the latest example of stocks of inexpensive, essential generic medicines hitting alarming lows. For example, there was a sodium bicarbonate scarcity in 2012 and a similarly alarming shortage of saline solution in 2014.

Experts blame the shortages on a combination of factors, including problems getting raw materials, issues with aging facilities where many old drugs are manufactured, and consolidation in the industry that reduces the number of potential suppliers. There’s also the concern that because generic drugs are unlikely to drive profits , drug companies may not make necessary investments to maintain supplies.

But when there isn’t a steady supply, patients suffer. With the shortage of sodium bicarbonate, hospitals are postponing surgeries and chemotherapy treatments. A hospital in Mobile, Alabama, for example, postponed seven open-heart surgeries and sent one critically ill patient to another hospital due to the shortage.

The Food and Drug Administration is working with Pfizer and Amphastar to try to mitigate the effects of the scarcity. A spokesperson for the agency said that it is “exploring all possible solutions to this critical shortage, including temporary importation, to help with this shortage until it’s resolved.”

In recent years, the agency has been addressing the problem of shortages and has made progress. In 2011, there were 251 shortages, while there were only 23 in 2016. There are currently 50 drugs listed in short supply.