Flea Treatment for CRF cat?

[PumpkinPal]

Hello everyone!

I searched the forum, but did not see any recent info.

We've got fleas. It's not bad, but I did see one black speck on Sampson earlier. Put water on it, turned red. I've combed all the cats, nothing showing
in the fur or on the comb.

I have used Advantage in the past with no adverse reactions. However, I am
concerned about using it on Sampson. He was diagnosed with early kidney
failure June of last year.

He is still on 100ml sub Q's 3 times a week. I give him 2.5 mg of Methimazole twice daily for his thyroid.

We had a vet visit 2 weeks ago. A little weight loss, but urine came back clean, BUN and Creatinine slightly elevated but better than his last test.

She did a full exam and everything else is fine. He still has a decent appetite and is not drinking much water.

I have read about the possibility of seizures. I am concerned about anemia.

Would it be ok to use on him? He's had on him twice before, never had a reaction but this was years ago before his current health issues.

I plan to ask the vet as well but also wanted to get feedback here.

Any help is appreciated.