Magnesium Trisilicate

Synonyms: E553(a); Magnesii trisilicas; Magnesio, trisilicato de; Magnésium, trisilicate de; Magnesiumtrisilikaatti; Magnesiumtrisilikat; Magnézium-triszilikát; Magnezyum Trisilikat; Magnio trisilikatas; Trikřemičitan hořečnatý.
Cyrillic synonym: Магния Трисиликат.

💊 Chemical information

CAS — 14987-04-3 (anhydrous magnesium trisilicate); 39365-87-2 (magnesium trisilicate hydrate).


Magnesium trisilicate is a hydrated magnesium silicate. The code E553(a) has been applied to both magnesium silicate and to magnesium trisilicate.


In Chin., Eur., US, and Viet.

Ph. Eur. 6.2

(Magnesium Trisilicate). It has a variable composition corresponding approximately to the formula Mg 2 Si 3 O 8 ,xH 2 O containing not less than 29% of magnesium oxide and not less than the equivalent of 65% of silicon dioxide, both calculated with reference to the ignited substance. A white or almost white powder. Practically insoluble in water and in alcohol.

USP 31

(Magnesium Trisilicate). A compound of magnesium oxide and silicon dioxide with varying proportions of water. It contains not less than 20% of magnesium oxide and not less than 45% of silicon dioxide. A fine, white, odourless, powder, free from grittiness. Insoluble in water and in alcohol. It is readily decomposed by mineral acids.

💊 Profile

Magnesium trisilicate is a hydrated magnesium silicate. It is an antacid with general properties similar to those of magnesium hydroxide. It may be given in typical oral doses of up to about 500 mg as required, although higher doses have been given.. When given orally it reacts more slowly with hydrochloric acid in the stomach than magnesium hydroxide. Magnesium trisilicate is often given with aluminium-containing antacids such as aluminium hydroxide, which counteract its laxative effect. Magnesium trisilicate is also used as a food additive and as a pharmaceutical excipient.

Effects on the kidneys.

The formation of renal calculi containing silica is unusual, but has been reported in a small number of patients. In most of these cases, stone formation was attributed to the prolonged, and sometimes excessive, intake of antacids that contained magnesium trisilicate.1,2
1. Haddad FS, Kouyoumdjian A. Silica stones in humans. Urol Int 1986; 41: 70–6
2. Lee M-H, et al. Silica stone—development due to long time oral trisilicate intake. Scand J Urol Nephrol 1993; 27: 267–9.

💊 Preparations

BP 2008: Compound Magnesium Trisilicate Oral Powder; Compound Magnesium Trisilicate Tablets; Magnesium Trisilicate Mixture; USP 31: Alumina and Magnesium Trisilicate Oral Suspension; Alumina and Magnesium Trisilicate Tablets; Magnesium Trisilicate Tablets.

Proprietary Preparations

Used as an adjunct in: Swed.: Deltison.
Published January 28, 2019.