Can flat feet cause other foot problems such as plantar fasciitis or bunions?

It’s definitely possible that your flat feet could be the cause of the other problems you mentioned. Flat feet can cause your feet to overpronate, which can stretch and put extra strain on the plantar fascia around the heel when walking and weightbearing. Overpronation also increases the strain on the inside of your foot around the area where bunions form, which increases the risk of developing a bunion. A good orthotic can help to raise and correct your flattened arches, simultaneously reducing the strain on your plantar fascia and bunions.