New to Magnesium? Test a small amount on your skin before using all over your body. If you have never used topical magnesium before, you might feel a tingling sensation. This is totally normal and will go away with time. As with all products, discontinue use if you develop any kind of rash. Shake the bottle before each use. Apply to desired location. Decongestant blends can be applied to chest or feet before bed.