The reason why is because of their effect on the brain.
Here’s what it’s crucial that you know.
Which Antihistamines May Lead to Weight Gain?

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Experts say they are less likely to contribute to weight gain, too.
But they emphasize that short-term use of antihistamines is generally not problematic.
If long-term use is necessary, you should speak with a healthcare provider about potential side effects and risks.
2018;4(1):e000392.