Magnesium oxide isn't bad for you and having bought those you may as well use them. Magnesium oxide is the form generally used by health professionals and there is plenty of research showing that repleting magnesium status with the oxide form is better than remaining magnesium deficient. So I have no worries about people using magnesium oxide.

It's just there may be and probably are better forms.

People with Fibromyalgia may well be best advised to use magnesium malate as malic acid not only helps remove aluminium from the body but being a natural fruit acid that is found in many cells in the body is useful for energy production by the mitochondria. When your body absorbs the magnesium it releases the malic acid.

Magnesium Citrate is also well absorbed and helps reduce bone turnover although it's also the form most recommended for those who wish to benefit from it's laxative properties so may be helpful if you have trouble.

So as we don't know how much of the chelate form, or the oxide form, is in the type you chose next time go for a form that is a bit more specific. There is a temptation for manufacturers to use more of the cheap stuff and less of the expensive stuff if they don't have to declare the percentages on the label.