A typical dose is 25 mg three times a day, but check with your doctor before taking any extra vitamins. Avoid odors that may trigger nausea. For example, when my wife was pregnant, I couldn't brew a pot of coffee in the house. Some women have an aversion to the smell of fried foods or garlic. Ginger, in the form of capsules, cookies or ginger ale makes some people feel better.
Capsules containing powdered ginger are available in health food stores.
A dose of 250 mg. Avoid having an empty stomach by eating frequent, small meals. Seasickness bands worn on the wrists press on acupressure points resulting in relief of nausea. These are available in pharmacies. There's no predicting what will work for you.