Quick answer
Flat feet means the arch of your foot is low or completely flat against the ground. For most people who have always had flat feet, this is just how their foot is built, and it doesn’t cause problems. The arch that develops or collapses later in life is the kind that often needs attention.
Two very different categories
This is the most important distinction:
Flexible flat feet
The arch is present when you sit or rise on your toes, but flattens when you stand. Common, often inherited, usually painless. Most kids with flat feet have this kind, and most outgrow it.
Rigid flat feet
The foot stays flat in all positions, including on tiptoe. More likely to cause symptoms or signal an underlying structural problem (in teens, often a tarsal coalition).
Adult-acquired flatfoot
Someone with previously normal arches develops a collapsing arch in their 40s–60s, usually from posterior tibial tendon dysfunction (PTTD). One important nuance: in its earlier, most treatable stages an acquired flatfoot is still flexible (the arch reappears on tiptoe), and only becomes rigid late. So don’t let a reassuring tiptoe test dismiss a previously normal arch that is newly flattening, especially with pain along the inside of the ankle.
Symptoms (when there are any)
Many people with flat feet have no symptoms at all. When symptoms occur, they may include:
- Pain in the arch or along the inside of the ankle, especially after standing or walking
- Tired, achy feet at the end of the day
- Swelling along the inside of the ankle
- Feet that turn outward (heel angles outward when seen from behind)
- Difficulty rising on tiptoes on one foot, a clue to PTT dysfunction
- Pain that travels: knees, hips, lower back can be affected by altered foot mechanics
- Asymmetry: one foot becoming flatter than the other (especially worth investigating)
Causes
Childhood flat feet
- Normal development: kids’ arches form by age 6–10. Before that, flat feet are normal.
- Family history: foot shape is largely inherited
- Hypermobility (flexible joints throughout the body)
- Tarsal coalition: abnormal fusion between bones (rare, can cause stiff flat feet in adolescence)
Adult-acquired flat feet
- Posterior tibial tendon dysfunction: the most common cause
- Trauma: fractures or ligament injuries to the foot
- Arthritis: rheumatoid or post-traumatic
- Diabetes: through a complication called Charcot foot
- Obesity: increases load on the supporting structures
- Pregnancy: relaxin hormone loosens ligaments; sometimes leaves residual flattening
What to do about it
If you have flat feet but no symptoms
Do nothing. Flat feet without pain or functional problems don’t need treatment. Special shoes, orthotics, exercises, none have been shown to “fix” asymptomatic flat feet, and your arch isn’t going to harm you.
Children with flexible flat feet
- Reassurance: most outgrow it without intervention
- No need for special shoes in most cases
- Evaluation if there’s pain, asymmetry, stiffness, or rigid flat feet
Adults with painful flat feet
This is where treatment makes a difference:
- Supportive shoes with a structured arch and firm heel counter
- Over-the-counter arch supports for mild cases
- Custom orthotics for moderate cases, designed for your specific foot
- Calf and Achilles stretching: tight calves worsen symptoms
- Strengthening: particularly the posterior tibial tendon (heel raises)
- Activity modification: temporarily reduce high-impact activity during flares
- NSAIDs for pain
- Physical therapy for tailored programs
- Ankle bracing for moderate-to-severe cases, particularly in PTTD
- Surgery: reserved for advanced cases that fail conservative care; ranges from tendon repair to bone-realignment osteotomies and fusions
When to see a clinician
- New flat foot in adulthood (especially one-sided)
- Pain in the arch, inside of the ankle, or along the foot
- Difficulty rising on tiptoes on one leg
- Foot that’s progressively flattening over months/years
- Swelling along the inside of the ankle
- Knee, hip, or back pain that started around the same time
- Children with one-sided flat foot, stiff flat foot, or pain
- Anyone with flat feet plus diabetes, closer monitoring matters
The bottom line
Flat feet ≠ a problem. Painful flat feet or flat feet that are getting worse = a problem worth evaluating. Don’t let anyone convince you that asymptomatic flat feet need expensive shoes or orthotics; they don’t.
Frequently asked questions
Are flat feet a problem?
Often no. Many people with flat feet have no symptoms and never need treatment. Flat feet become a problem when they cause pain (in the foot, ankle, knee, hip, or back), when the arch suddenly collapses in adulthood (posterior tibial tendon dysfunction), or when they contribute to other conditions like plantar fasciitis or bunions.
Can flat feet be fixed?
Flexible flat feet (the arch appears when you stand on tiptoe) can't be permanently 'fixed' but can be well-managed with supportive shoes, orthotics, and strengthening exercises. Rigid flat feet that cause significant problems sometimes need surgery. Children often outgrow flat feet, many adults' feet aren't truly 'flat' but rather low-arched without functional problems.
Do I need orthotics for flat feet?
Only if you have symptoms. Flat feet without pain don't need treatment. If you have foot, ankle, or knee pain that improves with arch support, custom or over-the-counter orthotics can help. Start with quality OTC inserts (Powerstep, Superfeet, Sole) before considering custom, many people get full relief from $40 inserts.
What are the best shoes for flat feet?
Look for: a firm heel counter, good arch support, a stable midsole (not too soft), and a wide base. Avoid minimalist or zero-drop shoes if you have symptoms. Stability or motion-control running shoes are designed for flat feet. For everyday wear, shoes with removable insoles let you swap in orthotics.
Do flat feet cause back pain?
They can, collapsed arches change leg alignment, which affects the pelvis and lower back. The connection isn't universal, though. Many people with flat feet have no back pain. When flat feet do contribute to back pain, supportive shoes or orthotics often help. If back pain dominates, address that directly while also supporting the feet.
Are flat feet hereditary?
Yes, often. Foot shape (including arch height) is largely inherited. If both parents have flat feet, their children frequently do too. Some flat feet are acquired through injury, weight gain, pregnancy, or aging, particularly when the posterior tibial tendon weakens, the arch can collapse in adulthood (adult-acquired flatfoot).
What causes flat feet?
Most flat feet are simply inherited foot shape: the arch never fully develops in childhood, and that flexible type is usually painless. Flat feet can also develop later in life. The most common adult cause is posterior tibial tendon dysfunction, where the tendon that holds up the arch stretches and fails. Other contributors include foot or ankle injury, arthritis, excess body weight, and normal age-related tendon weakening. A foot that was not flat and becomes flat, especially one side with new pain along the inner ankle, deserves an exam rather than a shrug.
Are flat feet bad for you?
Usually, no. Most flat feet cause no pain and need no treatment, and plenty of high-level athletes have them. The picture changes when symptoms show up: aching arches or heels, feet that tire quickly, swelling along the inner ankle, or knee and hip pain from altered alignment. Symptomatic flat feet respond well to supportive footwear, arch supports or orthotics, calf stretching, and strengthening. The foot to take seriously is the one that changed: a newly flattened arch on one side is a tendon problem until proven otherwise.
Are flat feet congenital, or do they develop later?
Both patterns exist. Children naturally have flatter feet while the arch develops through roughly the first decade, and in some people a flexible flat foot simply persists lifelong, which is congenital and usually harmless. A rarer congenital form is a rigid flat foot from tarsal coalition, where two foot bones are abnormally joined. The developed-later version is adult-acquired flatfoot, most often from posterior tibial tendon dysfunction. Distinguishing which type you have changes the treatment, which is why a stiff or newly flattened foot warrants evaluation.
Sources
Last updated: July 16, 2026
About the author
Written and reviewed by a Doctor of Podiatric Medicine (DPM) practicing in Arizona for 6+ years. Board-certified by the American Board of Podiatric Medicine (ABPM); graduate of Midwestern University Arizona College of Podiatric Medicine.
Last clinically reviewed: July 16, 2026