Bars are open and in many cases struggling to meet their staffing needs. But now, many bartenders are also missing a key ingredient: alcohol.

In Killington, Vermont, Patty McGrath’s Irish Pub just got troubling news from its distributor: The supply of Guinness beer may be limited.

“Well, that would certainly put a dent in things. We are the biggest seller of Guinness in the state of Vermont,” McGrath said.

They need it for pints, of course, but they also need gallons for their Guinness stew. But can’t they just switch it with another stout?

“No … no, I’m not sure that’s a possibility,” McGrath said.

Vermont is one of several states reporting alcohol shortages.

Mandrake Bar in Los Angeles is having problems too. Reopening has been like starting a new business, said owner Flora Wiegmann.

“It really was building a new menu and then building the new menu again based on what was available,” she said.

Wiegmann said bourbon, tequila and wine are among the orders that kept getting delayed.

The holdups left many bars in a tight spot after already being closed for months, according to Reid Beckers, with Classic Beverage of Southern California — one of Mandrake Bar’s suppliers. From his perspective, a step up the supply chain, the alcohol is there, but there are shortages of labor and materials.

“Glassware. Glassware is just a killer. Even if you have the product ready, you can’t get it packaged,” Beckers said.

Kegs and aluminum cans are also hard to come by.

Inefficiency is a function of the industry, said Patrick Anderson, CEO of Anderson Economic Group. After the Prohibition era, he said, each step of the supply chain was regulated.

“One of the reasons for the system we have is temperance … meaning we’re not really encouraging you to drink. And the second is to levy taxes,” Anderson said.

So when demand is hot and there’s a shortage in one place, the whole system slows down for the sake of moderation.