What is hypomagnesaemia?

Information for the public

Hypomagnesaemia is a condition in which someone has abnormally low levels of magnesium in their blood. The condition can occur if people do not get enough magnesium in their diet, if they are not able to absorb magnesium properly, or if they lose too much magnesium in their urine.

Hypomagnesaemia can happen for a number of reasons, including if a person:

has malnutrition or diarrhoea
is taking certain types of medicines such as proton pump inhibitors (which reduce the amount of acid made by the stomach), diuretics (which help people lose water from their bodies), antibiotics (generally used to treat infections), some chemotherapy drugs (used to treat cancer), or immunosuppressants (drugs that weaken the immune system)
has certain inherited kidney conditions, such as Gitelman's syndrome, or
has had part of their small intestine removed (the small intestine is where most magnesium is absorbed by the body).

Often hypomagnesaemia does not cause any symptoms, but if someone's magnesium levels are low enough it can cause problems such as muscle weakness and tremors, seizures, and irregular heart rhythms. If someone has symptoms caused by hypomagnesaemia, they are often treated with an infusion (or 'drip') of magnesium into a vein (intravenous infusion). Sometimes they are given an injection of magnesium into the muscle (intramuscular injection) instead, or an oral magnesium supplement, usually in the form of a tablet. Oral magnesium supplements are also used to prevent hypomagnesaemia from coming back, which is the focus of this evidence summary.