Hello and thank you for your question.
I would advise your mom NOT to take Lasix without discussing it with her doctor first.
Lasix is a strong diuretic and can potentially disturb electrolytes and dehydrate kidneys even with one dose (especially in elderly patients - you did not specify your mom's age). Also, taking one dose of Lasix will not improve her edema.
Unless her edema becomes very painful, she should wait until Monday to see her doctor. In the meantime, she can elevate her legs as much as possible. She might need to phone her doctor if she develops a lot of discomfort in the legs.
I hope you find this information helpful. Please feel free to follow-up with any other questions you might have.
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