Simethicone - what happens if a newborn is given double the recomended dose?

I do realize this answer is a bit late - If it's just a single dose given by mistake it shouldn't really cause too much harm. Just need to keep an eye on the infant.

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

This is not a complete list of side effects and others may occur.

An overdose of simethicone is not likely to cause life-threatening symptoms.

http://www.drugs.com/mtm/simethicone.html