Foot bunions are caused by uneven pressure being applied to the joints and tendons in the feet, according to Mayo Clinic. An imbalance of pressure, heavy or shifting weight weakens the integrity of the joint in the big toe, causing parts of the joint to mold into a hard knob that protrudes from the foot.
It is not definitively known if narrow, tight or high-heeled shoes can cause or contribute to the formation of bunions, as of 2015, notes Mayo Clinic. Foot bunions can be caused by an injury to the foot or deformities that were present at birth. Some people inherit a foot type that causes bunions. Performing activities that frequently put excessive stress on the feet and big toe can cause bunions. Foot bunions may also be caused by some types of arthritis, such as rheumatoid arthritis or other types associated with inflammation.
It is important to see a doctor, podiatrist or orthopedic foot specialist if there is a visible bump on the toe joint, if the pain in the foot or toe persists, or if the bunion decreases mobility in the toe or foot, recommends Mayo Clinic. Although bunions seldom require medical treatment, it may be prudent to seek medical assistance if the bunion makes it difficult to find shoes that fit correctly.