Athlete's foot is a simple enough condition to understand it's a fungal infection that is caught from an infected person but its treatment may not be quite so straightforward.
There's a whole range of treatments available from the pharmacy, and it's very important to be specific about the type of infection you have.
If it is a wet, soggy type, then the preparation will be quite different from that used to treat the dry kind. Similarly, if the infection is cracked, you need to be more careful about the type of application you use.
For wet, soggy infection, preparations that include aluminum acetate can help, as can those that contain aluminum chloride, although note that this latter chemical can cause irritation, and is toxic by mouth and when inhaled.
Skin irritation and hypersensitivity reactions can occur with any of the preparations; diabetics in particular should avoid any treatments that include salicyclic and benzoic acid as these can trigger circulatory problems.