My experience with using topical mag oil is that it requires application on an as needed basis in order to obtain the pain relief aspect of mag oil. Same for muscle cramps, apply as needed. I do not find the relief that mag oil offers to be cumulative. Like most topical pain relievers, reapplication is needed in order to maintain the effect. The relief is usually felt within 5 to 15 minutes in most people. I have seen in one or two cases where it took longer, but the effect is usually felt in 15 minutes or less. When used for muscle cramps, the relief is usually felt in 5 minutes or less. Sometimes combining topical magnesium with oral magnesium offers a slightly better effect, but the topical mag oil offers the highest local tissue concentration and best pain relief and muscle relaxation when compared to any oral magnesium product. Max pain relief from mag oil is usually felt within 20 minutes. If that does not offer enough pain relief, something stronger is needed such as Stopain topical pain reliever.
One thing that I have noticed is that, when the effects start to wear off, I have a spray bottle of water which I can spray on the area where I applied the mag oil and rub it in a little and it reactivates the residual magnesium on the skin and works as if I had applied another application of mag oil again. This would be important for people with sensitive skin because mag oil can be mildly irritating for sensitive skin. I don't use it myself, but I understand that a little lotion can be substituted for the water spray application.
For those with more sensitive skin applying a little lotion right after applying the mag oil can also make it less irritating. Mag lotion does the same, but doesn't allow you to alter the ratio of lotion to magnesium.
Magnesium Oil Applications Tips
I make my own magnesium oil. I have used vodka and magnesium flakes, as I believe Art has recommended, to make it and it does feel less sticky. I use it on my lower back or shoulders for tight muscles, pain, nerve pain, etc.
However, in the colder months I found that I was hesitant to use it because I didn't like spraying something cold onto my back; that makes me tense up. When it is cold I have found that spraying the oil into my palm and then applying it makes it much more tolerable. It is easier to apply it to my back this way anyway. I follow up with a homemade Tiger Balm type salve and this prevents it from making my skin itchy and I think contributes to pain relief.
~Mama to Many~
Mag oil is great for the human body and it has many health benefits which have been mentioned often on EC by many posters over the years. Mag oil also has some downsides that are not mentioned often, but two important issues are the fact that higher percentage mag oil can have a burning or stinging effect for some people, especially when applied to the neck and shoulder area. This is unfortunate because mag oil is very good for helping to relax the muscles in those areas and is often used for that purpose. One way to minimize this bad effect is to add MSM to the mix when you make your mag oil solution from flakes. I like to use 5 grams per ounce of water for this purpose.
Another downside to mag oil is the fact that even though it is not an oil, it does "feel oily" and can stay feeling oily for hours after you apply it, especially as you increase the percentage of flakes in your mag oil solution. One way to help reduce this sticky oily feeling is by using vodka in place of distilled water to make your mag oil with. The vodka reduces the oily feeling and also lessens the time that you feel oily or sticky by a very significant amount.
So these are two ways to make it easier to use magnesium oil which could also help with regular application compliance which should be better for your overall health!