Luke Weaver has an explanation for his struggles since arriving in Pittsburgh.

And it’s a pretty good one.

The ex-Mets reliever, who was dealt to the Pirates at the trade deadline, revealed this week that he has been battling a “severe” case of poison ivy for nearly a month.

“I’ve had my own set of personal challenges over the last month, and I’ve kept them to myself, but at the end of the day, I’ve had almost a month worth of severe poison ivy,” Weaver told DK Pittsburgh Sports on Thursday.

Weaver said the issue began in Miami in August, shortly after he joined the Pirates, when he brushed up against a bush.

“To the point where I’ve just been in hives over my entire lower body,” Weaver said. “Brushed up against a bush and my body went into a really bad state. I’ve been fighting my own personal battle with sleep. I haven’t slept in about a month, I wake up a lot. But that’s my own deal. I’m trying to find ways every single day.”

Weaver, traded for the Pirates’ No. 9 prospect, infielder Sammy Stafura, has posted a 5.79 ERA across 10 appearances since the deal. 

Before leaving the Big Apple, Weaver had a sparkling 1.84 ERA over 44 innings for the Mets.

“It’s been tough,” Pirates manager Don Kelly said, per MLB.com. “He got a really bad case of it. Just navigating that in a way, trying to help him. I know our medical staff has tried to help him as much as possible to get rid of it. It’s been tough to kick. It was a really tough case. He’s doing a lot better now.

“It’s been going on for a little while.”