There around 30 types of Hoodia plants in the world, they are very common in Mexico. The Hoodia that is native to South Africa is the only variety that contains the molecule P57, this is the active ingredient that controls appetite. There are some companies selling Hoodia products who use Hoodia from other parts of the world.
These products are inferior in quality and will not give you the results you are looking for. Some manufacturers are also combining Hoodia with other items to create their products, the best results come from products are pure Hoodia extract. Hoodia extract is very expensive and this is part of the reason some companies try to combine it with other cheaper herbs.
You should only consider purchasing 100% pure Hoodia products. Hoodia Gordonii may take up to 14 days to work. While some users have reported immediate effects, others have reported the effects gradually becoming stronger. Some has taken as long as 2 weeks to feel the full effects.