Instruct: Classify a given review into positive or negative sentiment.
Query: Counterfeit. Do not buy!

My 2 year old cat uses Cosequin for his bladder. The initial bottle we got from the vet worked perfectly and he no longer had urine crystals. A short time after we started him on the bottle we ordered from here, he lost weight, drank water CONSTANTLY (even slept by his water bowl), had no personality, and was very lethargic. After about a month of this, we remembered one other review that indicated these pills may not be legitimate, and immediately stopped giving them to him. Now, after buying a bottle from Petsmart, he is back to his old self: gained weight, drinking water normally, and interacting with us. I will never buy medicine online again and am mad at myself for making that mistake in the first place. I hope this review will prevent someone else from making the same mistake!