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Took mebendazole tablet 100mg for thread worm. Will this cause any harm on the fetus?

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Dear Doctor: I took 1 mebendazole tablet 100mg a couple of days ago for thread worms and just found out that I am about 5 weeks pregnant and i have read that it is not to be taken in pregnancy and I am panicking about the side effects to the baby what can I do?
Posted Thu, 22 Nov 2012 in Medicines and Side Effects
Answered by Dr. Timothy Raichle 1 hour later
Hello, I would be happy to help you with your question.

Here is a quote from a reputable source:

"Adverse events have been observed in animal reproduction studies...Adverse pregnancy outcomes have not been observed following use in pregnancy XXXXXXX

In pregnancy, it is considered a Category C medication. This means that it is uncertain whether there is harm, but it is presumed that what you have taken thus far is unlikely to be of any harm.

If you needed to be treated further in the current pregnancy, then the usual recommendation might be to wait until you are well out of the first trimester. Talk with your doctor about your concerns, but rest easy knowing that it is very unlikely that you have done any harm to your unborn child!

I hope this helps!! Please remember to provide feedback for my answer!
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Follow-up: Took mebendazole tablet 100mg for thread worm. Will this cause any harm on the fetus? 2 hours later
Thank you for the reply that was helpful my only other question is as the pregnancy progresses are there any tests which can be done to pick up any harm or birth defects that a baby would have if by any chance that the drug caused harm though i understand there is unlikely to be any harm caused.
Answered by Dr. Timothy Raichle 13 hours later
The standard screens in early pregnancy might include:

1. First trimester screening with Ultrasound / labs to detect genetic problems such as Down's syndrome
2. AFP lab draw at 16 weeks to detect defects in the spine
3. An ultrasound at 20 weeks to look for anatomic problems.

These are standard in any pregnancy. As I stated, there were no specific reports of specific defects caused by the medication you took. I stand by my prior answer.

Good luck!!
Above answer was peer-reviewed by
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