I am 28 weeks pregnant with my second child and I have bad diarriaha for about 18 hours I never happened in my first pregnancy

You should call your Physician - it cpuld be anything or nothing and, of course, it is dangerous to take anything over the counter while you are pregnant.

I got that from time to time with my second pregnancy... could be a number of things.. but if you are concerned you can do as katee says and call your physician... wouldnt hurt.. you can probably have the answer by the end of the day without having to be seen and if they feel you need to be seen they will tell you to come in...

A helpful tip... next time you see your doctor or midwife, make a list of the medications they are comfortable with you taking while pregnant.

Find out what you can take for upset stomach/diarrhea, cold/flu congestion, sore throat, etc. so that you will know what they prefer should you experience those types of complaints.

Hope you feel better soon!