Good point Sally. There isn't a cream of that sort that I know of because it would probably cause skin irritation as Epsom salts can be quite drying even when mixed into a bath. Showering off a bit helps to avoid that side effect by the way.

A very effective alternative to the Epsom salt bath is an Epsom salt poultice and it isn't hard to prepare and then have on hand to be used as needed. The solution can be applied warmed, cool or cold to small or large areas. This poultice is also very good for sprains and to ease local inflammation due to things like sore injection sites (like the ones that vaccinations cause), bruises, insect stings etc.

For the solution:
Into a large cooking pot, mix around 10 Cups of Epsom salts into a couple gallons of water. Bring it to a boil and simmer until the Epsom salts dissolve. This creates a hypertonic solution which is much stronger (more effective), than the one that is made when mixed into a bath. One shouldn't make too strong of a solution in a bath though because the body can absorb too much magnesium and that could create an electrolyte imbalance if repeated too often.
Store the prepared solution in a cool place. A bucket with a lid or gallon water jugs work very well for this. When you want to use it, a small amount can be heated on the stove or used just as it is.

For the Poultice:
Soak a small towel in the solution and wring it out lightly. Wrap that around the sore body area and cover that with some plastic to keep the moisture in. Household kitchen garbage bags work well for this. Then wrap that in another heavier dry towel which will keep a little heat in just that area. A bath towel is perfect. Let that stay on for around 30 minutes, then remove and either rinse or wipe the residue off the skin. Applying a moisturizer afterwards helps to prevent the drying effect.
After the poultice, doing a little stretching or applying a cool compress (for swelling), as the situation requires, may also be beneficial.

Hope that it works well for those who try it.