How long does nausea and vomiting last while pregnant I am 12 weeks and last night was up throwing up all night?

Varies. If you haven't had trouble with vomiting all along, this may be food poisoning. Most women will have their nausea get much better starting around 10 weeks and resolved by about 12. It is only dangerous if you can't keep anything in or keep losing weight. There are several prescription medications that are safe for pregnancy so let your OB know if you continue to have trouble.
1st trimester. Most of the time this is a problem of the first trimester, some women don't get it at all and some have issues almost throughout pregnancy. I hope your will end soon. A combination of vitamin b6 and doxylamine can help ease symptoms. This is an over the counter option that is approved and recommended by the american college of obstericians and gynecologists.