Magnesium Chloride, 80% solution

By Cat, 2019;  Image, right, from Step to Health (8) 

In my article Minerals: Magnesium (About) I discuss why magnesium is so important, foods that are high in magnesium, and supplemental forms of magnesium. In this article, I dig deeper into the use of the 80% Magnesium Chloride solution, both orally and topically.

See also a 2022 article about a new Nano Magnesium Chloride that I might try instead of the 80% solution version. In liquid form, it provides 100 mg magnesium/dropper-full; in capsule form, it provides 117 mg magnesium/capsule. I’d like to try the liquid form, instead of the 80% solution form. I note that the 80% solution I’ve been taking provides 95 mg magnesium/dropper-full.

Magnesium Chloride 80% solution

2019 with later updates.

80% solution means 80 grams (g) of substance in 100 milliliters (ml) of solvent. In this case, the “substance” is “magnesium chloride hexahydrate” (MgCl2.6H2O), with molecular weight of 203 grams/mole, and the solvent is pure filtered water. This is a very concentrated solution, providing 95 mg Magnesium per ml (20 drops) of solution (1 ml is approximately 1-eye-dropperful solution). Here’s the calculation:

  • Atomic weight of Mg = 24;
  • Molecular weight of MgCl2.6H20 = 24+(2×35)+(6x(2+16)) = 202 grams/mole;
  • Thus ratio of elemental Mg to MgCl2.6H2O flakes = 24/202 = 0.119
  • 80% solution = 80 grams MgCl2.6H20 in 100 miligrams (or 100 ml) water, or 800 mg/ml
  • 800 mg MgCl2.6H2O/ml soln.) x (0.119 ratio) = 95 mg/ml
  • Thus 1 ml (20 drops or about 1-dropper-full) solution provides 95 mg Magnesium
  • Or said another way, 80% solution of hydrated MgCl2 provides about 95 mg Magnesium per ml (20 drops) of solution (or 95 mg per eye-dropperful solution):

Originally I took about 2 ml 3-times per day, or 570 mg Mg per day. But I later developed a food sensitivity to it, and have since reduced my dosage to 1 ml (20 drops) 3-times per day, beginning Jan 2022. That current dosage provides 190 mg of MgCl2/day. It isn’t enough (I have symptoms of magnesium shortage), but it keeps the food sensitivity at-bay.

Although you can purchase the flakes to make your own at home (see below), it is very important to do so in a sterile environment, using sterilized equipment and pure, clean, filtered water. You also have to use an accurate scale that measures in grams. Because all this is hard to do in your home, I get mine from a compounding pharmacy as a prescription from my naturopath.

You should refrigerate your bottle(s) when not using.

How to access Walter Last Original article

Walter died in 2021, and his website is no longer active. Thankfully, I saved the original article and a 2008 updated version as pdfs:

How to make and use the 80% solution (from magnesium chloride hexahydrate flakes)


You must work in a sterile space and use sterilized equipment when making your own 80% solution. Store it in the refrigerator, and use within 30 days.

These instructions are originally from my iWeb Health-Systemic section, Acid-Alkaline Balance article.

What you need (substance and equipment):

  • Use exactly:
    • 80.0 grams MgCl2.6H2O flakes;
    • 100 grams (or 100 ml) pure, filtered water;
  • A sterile glass jar or other glass container; 
  • Sterile spoon or other sterile mixing tool;
  • Sterile glass jar fitted with sterilized eye dropper, for storage and usage


  1. Sterilize container and spoon.
  2. Measure the flakes and place in glass container.
  3. Measure water and add to the flakes.
  4. Stir until dissolved (it takes awhile).
  5. Once dissolved, transfer a portion to the storage bottle with eye dropper for usage.

Hydrated MgCl2 (MgCl2.6H2O) in powdered/flake form contains about 120 mg of Mg per gram, or 400 mg per level teaspoon. Cat’s 9/1/23 note: The original link to Walter’s Magnesium Chloride article is no longer online. Thankfully I saved his original and later articles as pdfs, which you can access :

  • Original article: MgCl2-WalterLast.pdf
  • MgCl2-WalterLast-II_2008-1.pdf

80% solution of hydrated MgCl2 provides about 95 mg Mg per ml of solution:

  • atomic weight of Mg = 24; of MgCl2.6H20 = 24+(2×35)+(6x(2+16)) = 202;
  • 80% solution = 80 grams MgCl2.6H20 in 100 grams (or 100 ml) water;
  • 80 g MgCl2.6H2O/100 ml soln.)x(24 g Mg/202 g MgCl2.6H2O) = .095 g Mg/ml solution

To take it orally:

  1. If you’ve never taken it before, start with ½ dropper-full (10 drops) of the solution added to 8-oz glass of water, 1-3 times /day. Take just before a meal; I also take a dose before bed.
  2. Then slowly increase dosage over 1-2 weeks to 1 or 2 droppers full, 2-3 times/day.
  3. If your body reacts negatively (such as a food sensitivity), take a break for a week or more and start over with ½ dropper-full for 1-2 months before increasing.

How to take: Measure desired amount and add to an 8-oz glass of filtered water, before/with a meal and/or before bed. If you take herbal tinctures, you can add them to the water mix. You can take it 1 – 3 times daily.

To use an 80% solution as a spray or rub:

The 80% MgCl2 solution (hydrated MgCl2.6H2O) that I take orally provides about 95 mg of elemental magnesium per 1 ml of solution. This is a bit too strong to apply directly to the skin, but it can be diluted for that use:

Add 3 ml distilled water to 1 ml of 80% solution (total 4 ml liquid) to get about 24 mg Mg/ml of new solution (95 mg divided by 4 ml). Then use a spray bottle, or an eye-dropper which delivers approximately 1 ml of aqueous solution. 

Or, if that is too strong (irritates the skin), you can:

  • dilute 1 ml of the diluted sollution with more water. For example, add 1 ml of the diluted 80% solution (containing 24 mg Mg) to 3 ml water (total 4 ml liquid) to get about 6 mg Mg/ml of the further diluted solution; OR
  • use more water to dilute the 80% solution further dilute the diluted solution. For example, add 16 ml distilled water to 1 ml of 80% solution (17 ml liquid), to get about 6 mg Mg/ml diluted solution; or
  • spray the original diluted solution more often or over a larger area.

I opted to buy a pre-made spray (Life-flo brand). Unfortunately, it doesn’t indicate how much magnesium per spray; on the other hand, it didn’t irritate my skin.

Applying magnesium oil spray

Dr Axe (3) recommends:

  • Start with minimum use and work up to normal dosage slowly;
  • apply magnesium liberally to clean skin of torso, legs, and arms. Avoid sensitive areas and mucus membranes.
  • underarms are one of best places to apply for maximum absorption.
  • optional: rinse or wipe off after 20 minutes.

Cat’s note: My feet twinkle when I’m resting – especially in bed when I’m trying to go to sleep – so I rub some magnesium oil spray on my feet and rub it in all over the feet and ankles and especially between the toes, about 20-30 minutes before bed. It makes a big difference for me.

To apply the oil spray, he recommends:

Apply after a shower, when the skin is clear of lotions or other oils. After spraying, magnesium oil should be thoroughly rubbed in and left to absorb for about 30 minutes.

Depending on your preference, you can shower or wipe down to eliminate any residue. The first few times applying magnesium oil spray may result in some uncomfortable tingling. This sensation should dissipate the longer you use it.

To use as magnesium oil as scented deodorant:

Mix the following (from Dr. Axe (3)):

  • 4 ounces magnesium oil
  • 10–15 drops of your preferred essential oil

Spray or rub onto the underarms. [Cat’s note: I have not tried this.]

Other options I’ve tried

2021 update: Because of my food sensitivity issue with taking MgCl2 solution orally, I can lower the amount of Mg taken orally, and make up the difference with the topical spray and/or Epsom salt baths. 

For example, do two oral doses of the 80% solution added to a glass of water (each provides 95 mg Magnesium), and 2-3 topical doses of diluted solution topically.

  • If use 4 ml of the diluted solution that provides 6 mg Mag per ml or 24 mg Mag in 4 ml (as described above) 2-times, that adds 48 mg Mag for total of  (95 x 2 oral)+ (24 x 2 topical ) = 238 total mg Mag/day;
  • If use 4 ml of the diluted solution topically 3-times, that adds 72 mg Mag for total of (95 x 2 oral) + (24 x 3 topical) = 262 total Mag/day

The level of dilution can be adjusted to provide more or less magnesium. 

How to make and use Magnesium- & Potassium-Chloride Solution 

Apr 2011: My Naturopath wants me to try a mixed solution of MgCl2.6H2O (3.95% Mg)  and KCl (potassium chloride), taking 2.5 ml 4x/day or 10 ml/day, providing (per Evergreen Pharmacy, who make up the solution for me):

39.5 mg each Mg & K per ml [or 390 mg each Mg & K per day (@ 10 ml/day)] .

It is made with 156.25 g MgCl2.6H2O flakes plus 35.475 g KCl powder, with water added to make 473 ml solution. Given: 

  • Atomic/molecular weight: Mg is 24 g/mole; MgCl2.6H2O is 202 g/mole.
  • Atomic/molecular weight: K is 35.475 g/mole; KCl is 74.54 g/mole

I calculate as follows [NOTE:  ‘% composition’ is not the same as pharmaceutical % (g/100ml). (10,11)]:

  • Mg: (156.25 g MgCl2.6H2O) x (24 g Mg/202 g MgCl2.6H2O) = 18.564 g Mg (18564 mg) in 473 ml soln; thus 18564 mg Mg /473 ml = 39.2 mg Mg/ml
  • K: (35.475 g KCl) x (39.09 K/74.54 g KCL) = 18.60 g (18604 mg) K in 473 ml solution; thus 18604 mg K/473 ml = 39.3 mg K/ml

For Mg, this dose is ~360 mg Mg less per day than my regular dose (~400 mg*). I’ll use the 80% MgCl2 solution to make up the difference (OK per my Naturopath), as follows:

To start, I will make up 190 mg Mg (appx half the difference) by adding 1 ml of the 80% MgCl2 solution to my morning and evening doses of the Mg/K solution. And I will change to 3 doses/day, still achieving 10 ml/day of the mixed solution, as follows: Add to 10 oz water (beginning 4/22/11):

      • Morning 3 ml Mg/K solution plus 1 ml 80% MgCl2 solution
      • Afternoon: 4 ml Mg/K solution
      • Evening: 3 ml Mg/K solution plus 1 ml 80% MgCl2 solution

Try this for several weeks to see if improvements, and whether I can tolerate the Mg. If all is well, I’ll add another 1 ml Mg solution to Morning and Evening dosages.

June 2011 Update: I found I had to add another 1 ml 80% MgCl2 solution to morning and evening doses because the mixture didn’t provide enough Mg. When I used up the bottle of the mixture, I went back to my regular 80% MgCl2 solution, and added ½ tsp potassium chloride (KCl) powder to my smoothie.

2012 update: My annual fasting blood labs indicates too much potassium, probably because I use unrefined sea salt (instead of regular table sat), which provides a fair amount of potassium. So I stopped adding the KCl powder to my smoothie.

*In 2011 (when I wrote this calculation), I was taking about 400 mg Magnesium daily (from the 80% solution). As of my 2019 update, my dosage was about 570 mg Magnesium daily (from the 80% solution), and I’ve not been taking the Mg/K mixed solution since 2011. As of my Jan 2022 update, I’m only taking 1 dropper-full (1 ml) in water 3-times daily, because of food sensitivity. Since that low dosage leaves me constipated, I also take 1 capsule of Blue Heron supplement (Integrative Technologies) 3-times daily (before breakfast, in afternoon, and before bed.

** In Oct 2022, my food sensitivity to the MgCl2 solution was finally cleared. I slowly increased my 3-time daily dosage from 1 ml plus 3 drops in water to 3 ml plus 3 drops, and now continue at that higher dosage. My food sensitivity has not returned.


  1. Mercola:
  4. Walter Last:
  5.…/Magnesium Chloride Hexahydrate Therapy.pdf
  6. how: How to Extract Magnesium Chloride from Sea
  7. MagChloride-hexahydrate therapy:
  8. Image:
  12. Upgraded Formula’s Upgraded Magnesium products:
    1. capsule form (117 mg magnesium/capsule):
    2. liquid form (100 mg magnesium/dropper-full:

About Cat

See my 'About' page
This entry was posted in Diet, Health and tagged , , . Bookmark the permalink.