Hi, I have only just stopped taking this medication and even though in my experience I have to deal with weight gain with most psychiatric medication this wasn't the case when taking citalopram.
All medications effect people differently and obviously side effects can be issue. I would, if you are concerned, contact your doctor for advice. Even if it only reassures you it, you should always inform who treating you of any side effect you are experiencing, it may settle down if it is increasing your appetite.
I hope things settle down .
The common side effects of citalopram are loss of appetite... but it is best to either talk to your Psychiatrist or check out any suspected side effects on Drugs.com.