If I can only stomach a children's vitamin should I take double the recommended dosage?

Wondering why. Is it possible that you have actually gotten sick taken iron-rich vitamin-and-iron tablets? Perhaps if so, and you aren't someone who needs the extra iron, you can get a vitamins-only preparation. Most people have no trouble tolerating these.
Yes. Yes, most of the time doubling a children's vitamin should be safe, but check content also, since too much of certain vitamins can be embryo toxic such as vitamin a. Make sure you take at least 1000 mcg of folic acid. Dha, omega 3 fatty acid, is also recommended now, omega 3 fatty acids.