Can atarax (hydroxyzine) cause weight changes?

Possibly: Atarax (hydroxyzine) can cause nausea and vomiting in some, which will of course affect calorie intake. In more unusual cases, it can affect your appetite directly. SO weight changes are a possibility. Your history of gastritis suggests many other possibilities as well. It would be a good idea to discuss this with your doctor for further evaluation of these other possibilities.

Not likely: There are rare reports of hydroxyzine (Atarax) causing loss of appetite that can lead to weight loss. There are other rare reports of this drug causing decreased physical activity due to increased sleepiness that could lead to weight gain with prolonged use. Both are very rare.