Flat Feet: When They Cause Problems and When They Don't

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 (or acquired) flat feet

The foot stays flat in all positions. More likely to cause symptoms or signal an underlying problem. Adult-acquired flatfoot — where someone with previously normal arches develops a collapsed arch in their 40s–60s — is the most clinically important version. It’s usually caused by posterior tibial tendon dysfunction (PTTD).

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.