Allergic Dermatis & Flea meds together?

Just took the smallest of our 3 cats to the vet for what we discovered was a case of fleas (first ever in 4 years here, and 4 years before that -never had them at all) and discovered his problem is compounded by a flea allergy. The vet administered a shot of DEPO-MEDROL to control the itching and prescribed CAPSTAR tabs to dose him and the other cats, then to begin a Frontline Plus treatment plan.

I cannot remember if or why he said not to dose the little guy right with the CAPSTAR right away; I believe it is because of the corticosteroid shot he got. We do not want the cats to keep suffering and want to get them ALL dosed at the same time so they are not on different med schedules and get this situation sorted ASAP. Does anyone have any experience with this?

Of course, it is a weekend and I can't get the vet on the phone now to ask. We just aren't sure if there is a problem with Depo-Medrol and Capstar together, and we would really like to get the other 2 started immediately, if possible.  Any advice appreciated.

Just a quick update - we gave all the cats the Capstar and the little guy was OK. They all were a little nuts when it kicked in and the fleas started getting killed off - all them scratching and licking like crazy for about 2 hours or so. However, by the end of 4-5 hours, they all seemed so much happier, and very tired.

Next problem - we crushed the pill into a powder and got it in to them via their favorite treat - fish flakes. They are on to us - none of them completely finished their treat and usually are stalking each others treat dish to lick any residue. I am considering getting some pill pockets for them and see how that goes.

Today is comb the cats, do all the bedding and towels etc., they have been on, and then vacuum AGAIN. I intend to vacuum daily until this is over, which I hope is soon.