General warnings and precautions
Certain people should not take magnesium supplements at all:
- People that have had an ileostomy
- People with heart blockage (unless a pacemaker is in place)
- People with kidney failure
- People who have appendicitis
People that have had an ileostomy will not be able to absorb the magnesium properly, cause further intestinal blockages, which could cause seriously adverse health effects.
People with any type of heart blockage could experience a relaxing of the heart muscles and a slowing of the heart rate, causing inability of the heart to beat sufficiently.
People with kidney failure will not be able to eliminate the excess magnesium, cause high blood magnesium levels and cause further kidney damage.
People with appendicitis should not take any type of magnesium supplements as there may be an increased danger of perforation or rupture of the appendix due to the magnesium's constipating or laxative effects.
Certain people should not take magnesium supplements without first consulting their doctor for advice:
- People who have chronic constipation, colitis or diarrhoea
- Women who are pregnant or breastfeeding
People with the above conditions should get advice from their medical doctor before starting supplements to ensure magnesium supplementation does not conflict adversely with their condition.
Toxic Levels of Magnesium
Magnesium is toxic at doses greater than 15000mg (15g) per day.
People with appendicitis should not take any type of magnesium supplements as there may be an increased danger of perforation or rupture of the appendix
Overdosage and Toxicity Symptoms - Acute Toxicity
Acute toxicity from taking too much in magnesium supplements - over 15g can cause the following symptoms:
- Difficulty breathing
- Extreme muscle weakness
- Extremely low blood pressure
- Irregular heartbeat
- Severe nausea
* People who experience the highlighted symptoms should seek immediate emergency treatment.
Overdosage and Toxicity Symptoms - Chronic Toxicity
Chronic toxicity of magnesium from taking higher than the therapeutic dose of supplements for a long time can cause the following symptoms:
- Dry mouth
- Low blood pressure
- Mood changes
- Muscle weakness
- Sleepiness and lethargy
People who experience any of the above toxicity symptoms should discontinue their magnesium supplements and see their doctor for advice.
Overdosage and toxicity is more likely to occur from taking too many supplements, whereas dietary intake of magnesium is highly unlikely to cause overdosage.