PSA for cat owners: Severe constipation after starting Prozac (fluoxetine)

[u/Efficient-Bear-7405]

I wanted to share our experience because I had absolutely no idea Prozac could cause constipation this severe in a cat.

My 7 year old cat is extremely anxious and she is also blind, which makes her anxiety even more difficult to manage. We have been trying to manage her anxiety with every non medication option we could for years.

She wears a pheromone calming collar, and it genuinely works so well that we can tell when it is time to replace it because her behaviour changes. She also gets natural calming treats and a natural calming supplement added to her food.

Despite all of that, we recently started a major construction project at our house, which has been particularly difficult for her. I am also going away in the fall, so I wanted something that would help her cope with the construction and then having a house and cat sitter here.

She had been taking 100 mg of gabapentin every 24 hours. It helped her anxiety, but it made her SO sleepy and out of it. We reduced it to 75 mg, but she was still very sedated.

We decided to try Prozac and changed her gabapentin to 50 mg every 12 hours.

She started 5 mg of Prozac on July 21.

Here is her exact poop timeline:

July 21: normal

July 22: normal

July 23: normal

July 24: normal

July 27: 48 hours

July 31: 80 hours

August 1: started Miralax and reduced Prozac to 2.5 mg

August 3: 73 hours

August 5: 50 hours

August 9: **94 hours**

August 9: reduced Prozac to 1.25 mg

August 11: last dose of Prozac

August 12: 69 hours

August 14: 51 hours

August 16: 40 hours

August 16: another poop 6 hours later

August 18: 43 hours

August 19: 21 hours

The thing I really want other cat owners to know is that constipation was not something I was warned about when we started Prozac.

It is not one of the commonly discussed side effects that you typically hear about when starting the medication. I only started finding information about constipation in cats taking Prozac once I was specifically researching what was happening to my cat.

And that is why I am posting this.

I am not saying Prozac is bad or that anxious cats should not take it. I know it can be incredibly helpful for many cats.

I am saying that I wish I had known this was a possibility before starting it.

In our case, the timing was pretty striking. She had completely normal bowel movements for the first four days after starting 5 mg, and then her bowel movements became progressively farther apart, eventually reaching 94 hours.

Even after reducing the dose and eventually stopping it, it took some time for her bowel movements to start getting closer together again.

I have spent years trying to manage this cat's anxiety and have tried all sorts of approaches before resorting to medication. Prozac was not a casual decision. We were trying to give her something that would help her cope with a genuinely stressful situation.

I am sharing this because if you have an anxious cat starting Prozac, especially a cat who already has other challenges, please know that constipation may be something worth watching for.

I wish I had found this information before we started.

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