The right-hander had leads of 1-0 in the first inning and 4-3 in the fourth. Lohse surrendered Chad Tracy's three-run homer in the first and Chris Snyder's solo shot in the fourth.
Both long balls came with two outs, a big no-no.
"Nobody is going to be harder on myself than I am," said Lohse, who pitched seven innings and allowed four runs on six hits without a walk and four strikeouts. "That's four runs right there after we did a great job getting a lead. I just didn't hold up my end."
Snyder's home run on an 0-1 count was particularly damaging. Lohse had picked up two quick groundouts, and the Arizona catcher was the No. 8 hitter with the pitcher on deck -- an even bigger no-no.
A fastball left over the plate was sent into the left-field seats.
"You've got a lead and the eight-hole hitter, you don't want to do that kind of stuff with the pitcher coming up next," Lohse said. "I was pretty upset with myself. You don't want to make a mistake coming inside, which I did two times tonight. If you get hurt, get hurt away. Lesson learned. I'll try not to make that mistake, again.
"I thought early in the game, we did a poor job of executing pitches, especially with two outs," Reds manager Jerry Narron also lamented. "That was kind of disappointing."
The first homer, to Tracy, came on a full-count fastball that also sat over the plate.
"It was just a bad choice," Lohse said. "[It was] 3-2. I didn't care if I walked him. I had a base open, and I tried to throw one up and in and set something up for later at-bats. I end up throwing a strike. It wasn't good execution and a poor choice of pitches. Javy [Valentin] called a couple of other pitches and I shook to get to the one I wanted and just didn't execute it."
Lohse retired his final 10 batters and 14 of the last 15 -- with Snyder's homer the lone blemish in the groove. His mea culpa was a sign of personal growth. In his days with the Twins, he drew criticism for not accepting blame when things went wrong.
Yet the blame wasn't exclusive to Lohse on Tuesday. The Reds offense scored all of its runs on early home runs. Adam Dunn hit a solo shot in the first inning off D-backs starter Edgar Gonzalez that gave them the first lead. In the third, Josh Hamilton's first big-league hit was a homer to right field. It was immediately followed by Brandon Phillips' go-ahead homer to left field.
After that, they came up empty, none more so than the top of the 11th. Dunn's leadoff single and Ken Griffey Jr.'s walk put two runners on with no outs. The dugout called for Edwin Encarnacion to sacrifice bunt but fouled off a 2-0 offering from reliever Juan Cruz (2-0). In a 3-1 count, Encarnacion swung away and fouled out behind the plate to complete an 0-for-5 night.
"It's pretty obvious that Eddie didn't have a very good night," Narron said. "Two guys on and Eddie bunting and didn't make a very good attempt at it. We let him swing the bat, and he got ahead in the count and then he popped the ball up."
The Reds' fifth reliever, David Weathers (0-1), took over in the 10th and retired his first five batters in quick fashion. In the 11th, Conor Jackson singled to right field. Jackson scored from first base on Hairston's double.
That sent the Reds (4-4) to their third straight loss, the last two being gut-punching one-run defeats to the D-backs.
Hamilton, a rookie outfielder, might have had a play on the carom, but he let the ball zip past him toward the infield as Jackson came home. Even if Hamilton cleanly fielded the ball, the chances of getting the runner at the plate seemed slim.
"I came back in and asked Dunner if I had a chance to catch it, he said I didn't," Hamilton said. It was one of those things he said the only way they wouldn't have scored if I caught it and there was no chance of catching it. It runs through my mind if I should have played it off the wall and tried to keep the guy at third? It was one of those things, you try to react to it, and it comes out how it does."
In what became the running theme of the evening, the final hits came with two outs.
"They got three big two-out hits, and we didn't," Narron said. "It was as simple as that."