The important issue is to try and match the strength of the solution of the Epsom Salts so that water is drawn from the bowel in a process called osmosis. Osmosis is a biological process in cells where water travel through the cell walls to an are of higher salt concentration. Sometimes called reverse osmosis. Different people have a different salt concentration and therefor the ideal individual solution varies from person to person.
Magnesium is the chemical that causes osmosis. Magnesium comes in many forms including magnesium chloride, magnesium oxide, magnesium pidolate, magnesium gluconate, magnesium arginate, magnesium citrate, magnesium aspartate, magnesium hydroxide, magnesium orotate. More is known about magnesium sulphate because it is has a number of medical uses which have been well documented.
Epsom Salts will act as a laxative when used at the rate of 1 to 2 tablespoons in 8 fluid ounces of water. However, some people will react with a dose less than 1 teaspoon. The recommended dose varies between manufacture and country. The packet that I currently have says that the safe dose is 1 to 2 tablespoons with no other restrictions. Valu-rite says 2 to 4 teaspoons in 8 fluid ounces up to twice a day. These guidelines are well within the safe limits because the companies do not want to be exposed to a law suit. All this too confusing so its best to just follow the protocol to start with and then tailor the dose rate if required. I have found that my effective dose is 2 teaspoons per 6 fluid ounces.
The medical experiments that demonstrated the contraction of the gallbladder with Epsom Salts used a solution of 25 grams to 100 ml this equates 5 teaspoons in 4 fluid ounces.