Cat threw up comfortis. Should I give him another dose?

I give both my cats comfortis for their flea prevention. This is their fourth treatment. So far it's been 50/50 them keeping it down/them throwing it up. My vet still believes it's the best flea treatment for them despite the issues with them throwing it up. I give it to them after they've eaten a little bit to line their stomachs and leave their food/water out so if they want to eat a little more after the pill they can. This time only my male cat threw up his pill. The label says that if they throw it up within an hour to give them another dose. My cat threw it up somewhere close to 55 minutes (it was between 53 and 55 minutes; that's as close as I can narrow it down). Obviously that's really close to the one hour mark. The other time this happened, I asked the vet if I should give them another dose when they threw up really close to an hour after getting the pill and she said if it was close to an hour it was fine; but the label says if it's within an hour to give them another dose. When I didn't give them another dose at the vet's advice they did still have some fleas but not as many as before they got the medicine. Do you think I should give him another dose since it was under the hour mark or should I not since it was so close? The main thing I'm worried about is if he did absorb some or most of the medication, I might overdose him a bit. He's at the lower end of the dosing chart. Does most of the medication absorb within the hour or is it completely ineffective if thrown up within an hour? Should I give him another dose or not?

I would NOT give him another dose.  Please call your vet on this because this stuff can be very dangerous if overdosed.  

Don't give another dose because you don't want to cause a toxicity if he was able to digest it.

And look into using the Seresto collar in a month if they can't keep the pill down. It's great and it lasts 8 months.

I would look for a topical flea treatment. I have had good luck with Revolution. It does have an alcohol smell to it so you may want to have the cat on your lap for 10-15 minutes after applying. Some cats don't like the smell and dart off and try to lick. I fixed that by having my cat make biscuits in her blanket, then put the ointment on her back of head/neck and keep her interested in biscuit making  then it gets soaked in and no licking..other times I have played with her having her chase her toys and wand toys.

Is there a reason you can't use Revolution? I also wouldn't use revolution so soon after this medication. And I wouldn't give another dose. There's a reason they vomit up the medicine. Obviously it's making them sick. You will need to either cut down the dose or use another product. I would not keep giving them the medicine and have them vomit.

Next time if you really need to use it-have them eat a whole meal. wait 15 minutes then administer. But not today.

General rule of thumb: if you're not sure if the cat got the whole dose, whether the pill was spit up entirely or paritally (right away or sometime later) or not all of all iquid got swallowed (or thrown up later), do not give another dose. You do not want to accidenally OD the cat. Just skip the dose and continue with a normal dose at the next scheduled dose time and call the vet for advice.

Do you use Pill Pockets to hide the pill in or are you just utting the pill directly into the cat's mouth?

Can you use a topical treatment like Revlution? Or one that is a liquid that is mixed into food (Program has one)? Or a chewable pill? Sometimes vet have a preference for one brand of medicine over others but should be able to give you a different brand if you specifically ask for it and explain that pills are difficult to give. Many can be bought online from a pet pharmacy or supply place. A prescription may be needed or at least the vet's phone number so the place can call to confirm.