The most commonly used supplements are magnesium, coenzyme Q-10, feverfew, butterbur and riboflavin (Vitamin B1). There are many other herbs and vitamin supplements that are cited on the web, but there are the ones that have the best clinical evidence to support their benefit.

The safety in pregnancy is not well established for some of these agents; please consult your doctor if you are pregnant or are planning to become pregnant and you are taking any of these products.
Butterbur (Petasites hybridus) is an extract of the butterbur root, which is a perennial shrub.

There are a couple of trials that have found this herb to be minimally beneficial in migraine prevention. The recommended dose was 75mg twice a day was effective and well tolerated by patients for migraine prevention. Upset stomach, especially burping was the most common side effect. Butterbur has been associated with liver toxicity, so if you have liver disease, you should not take this medication. Maximum response was seen 3 months after taking the drug.
Coenzyme Q-10 is a vitamin supplement, which is involved in many of the energy producing reactions in your body. It is also a powerful antioxidant. It is found in certain foods, including fish (salmon and tuna), meat and whole grains. It has been shown to be effective for migraine prevention. The recommended dose was 100mg three times a day.

This showed a greater than 50% reduction in the frequency of migraine attacks. This medication is well tolerated, and minor side effects included nausea and diarrhea. The data suggests taking the drug starts to work in 4 weeks, but often 5-12 weeks is needed to see significant reduction in migraine headaches.
Feverfew (Tanacetum parthenium) has been the herbal medication most studied for the prevention of migraines.

The research is conflicting on the benefit of the drug; some show evidence that the drug is beneficial whereas others show no benefit of the drug for migraine prevention. Use caution when taking this drug if you have diabetes, alcohol dependence or liver disease. You should not take this medication if you are pregnant or breast-feeding. Caution is also recommended in combining feverfew with anticoagulant medications, which are blood thinners, such as Coumadin (Warfarin). The current recommendations from the Canadian Headache Society (CHS) is against the use of feverfew.

Magnesium has also showed mixed results of its benefit in migraine prevention. Studies have shown that people who suffer migraines, have lower levels of magnesium during migraine attacks. Low magnesium may also play an important role in menstrual migraines. Magnesium is well tolerated, but at higher doses, diarrhea and stomach upset were commonly reported. Magnesium is found in our diet, including spices, nuts, cereals, coffee, cocoa, tea, leafty vegetables, gains and nuts. The current recommendation is to use 600mg daily.

Riboflavin (Vitamin B2) is found in lean meats, legumes, nuts, green leafy vegetable and dairy products. Studies have shown a 50% improvement in frequency of headaches, headache days and severity of headaches. The recommended dose according to the study was 400mg per day, but the effects were not seen until 3 months of taking the drug.

The drug is well tolerated, but mild side effects including numbness, itching and tingling have been noted.
These agents can be used in combination, since their effects can be synergistic, meaning, that the overall effect of using them together is greater than the effect of them alone. They work well together to help prevent migraines and there are no serious interactions when combined. Talk with your doctor to see if any of these herbal or vitamin preparations might work for you!