I think magnesium chloride may be best used topically. The more popular option as an oral supplement seems to be chelated magnesium glycinate. My pharmacist recommended this for magnesium deficiency because it has very high absorption. The downside to oral supplements is that they sometimes cause upset stomach or diarrhea. Magnesium citrate is known for causing diarrhea. That's why it's sometimes used for its laxative effects.