No. You do not need to worry about overdosing when using transdermal magnesium as upper limits are only set when using the product orally.
Large doses of oral magnesium can have a laxative effect due to it being a natural relaxant, however this is avoided when using magnesium applied to the skin.
Toxic symptoms from increased magnesium intake are not common as the body eliminates excess amounts, unless there are serious problems with kidney function.
