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It is not at all advisable to take drugs without your doctor`s advise.Cetirizine
can be used in pregnancy
but should be used with caution.
For your cold and fever , take hot vapor .For your diarrhea
keep drinking lots of fluids to avoid dehydration
as you have to maintain good fluid for your baby too.
Please visit your Obstetrician for treatment plan.
Take care and Good luck.