Leather shoes can be stretched using a homemade spray made of equal parts of isopropyl alcohol, also known as rubbing alcohol, and water. This concoction is sprayed liberally on the interior with special attention paid to any tight areas. Leather naturally has some give to it, but the alcohol helps it stretch further to conform to the shape of the foot without damaging the material.
For non-leather shoes, Good Housekeeping warns that rubbing alcohol reacts badly to some modern shoe materials and suggests stuffing small jars of the appropriate size into the shoes to stretch them overnight. Another method is to wrap a clean, dry mop head in a plastic bag before inserting it into the shoe.
Made Man recommends filling plastic bags with water and placing them inside the shoe. The water level should approximately fill the shoe. Place the shoes in the freezer overnight. As the water freezes, the forming ice gradually stretches the shoe. However, Made Man cautions that this method, though effective, does not fit the shoe as closely to the natural form of the foot.
A Fine Pair of Shoes, a UK-based shoe company, stresses the importance of caring for leather shoes by cleaning and conditioning them regularly to protect them from environmental damage. After shoes are stretched, condition them to prevent cracking.