A bunion (sometimes misspelled “bunyan”) is a bony bump that forms at the base of your big toe, where the toe meets the foot. It develops when the big toe gradually angles inward toward the smaller toes, pushing the joint at its base outward. About 23% of adults between 18 and 65 have one, and that number climbs to nearly 36% in people over 65.
The medical name is hallux valgus, and it’s one of the most common foot deformities. What looks like a simple bump on the surface is actually a misalignment of the entire joint, involving bone shifting in multiple directions.
What Happens Inside the Foot
A bunion isn’t new bone growing on the side of your foot. It’s the head of the first long bone in your foot (the metatarsal) pushing outward as your big toe drifts toward the second toe. The joint between these two bones becomes increasingly misaligned over time.
Advanced imaging shows the problem is more complex than it appears from the outside. The metatarsal bone doesn’t just shift sideways. It also rotates and tilts, which destabilizes the surrounding structures and displaces the small bones (sesamoids) that sit beneath the joint. This is why bunions tend to get progressively worse rather than staying the same size.
Causes and Risk Factors
Scientists suspect bunions result from a combination of genetics and lifestyle, though the exact causes aren’t fully settled. In children and teenagers who develop bunions, the condition tends to be linked to inherited joint deformities. In adults, inherited foot shape, structure, and the way your foot moves during walking all play a role in your susceptibility.
Tight shoes, high heels, and narrow toe boxes have long been blamed for causing bunions, but the relationship is more nuanced than that. Research suggests poorly fitting shoes probably don’t cause bunions on their own. Instead, they likely accelerate the problem or make it appear earlier in people who were already predisposed. Other risk factors include rheumatoid arthritis, osteoarthritis, and flat feet.
What a Bunion Feels Like
The most obvious sign is the visible bump itself, which you can both see and feel on the inside edge of your foot near the big toe. But the bump is often just the beginning. Common symptoms include:
- Pain or stiffness in the big toe, especially when walking or wearing shoes
- Swelling and redness around the joint
- Limited movement in the big toe, sometimes with a burning sensation when you try to bend it
- Corns or calluses where the first and second toes rub together
- Numbness in or around the big toe
Many people first notice a bunion not because of the bump but because their shoes stop fitting comfortably. Pain that worsens with certain footwear is one of the earliest complaints.
Complications From Untreated Bunions
A bunion that progresses without management can create problems beyond the big toe. The shifting joint changes how weight distributes across your foot, which can trigger a chain reaction of issues.
Bursitis is common: the small fluid-filled cushions near the joint become inflamed and painful. Hammertoe frequently develops in the second toe as it gets crowded by the drifting big toe, creating an abnormal bend in its middle joint. Metatarsalgia, which is pain and swelling in the ball of the foot, can also develop as pressure patterns change across the forefoot.
How Bunions Are Classified
Doctors evaluate bunions using weight-bearing X-rays that measure two key angles: the angle of the big toe’s deviation and the angle between the first two long bones in the foot. These measurements determine severity:
- Mild: The big toe angle is under 30 degrees, and the space between the first two metatarsals is less than 13 degrees
- Moderate: The big toe angle falls between 30 and 40 degrees, with 13 to 20 degrees between the metatarsals
- Severe: The big toe angle exceeds 40 degrees, and the metatarsal spread is greater than 20 degrees
These classifications guide treatment decisions, particularly whether surgery is warranted and which type would be most effective.
Non-Surgical Treatment Options
Conservative treatments can’t reverse a bunion, but they can slow its progression, reduce pain, and improve day-to-day comfort. The most effective non-surgical approach, based on a systematic review of available research, involves orthotic devices with a toe separator. These work by gently realigning the big toe position, relieving strain on the stretched ligaments around the joint.
A full-length orthotic with a built-in toe separator showed the best corrective results in studies, reducing the bunion angle by nearly 6 degrees. Custom-molded toe separators and nighttime splints showed more modest corrections of about 2 to 3 degrees. While these numbers sound small, even a few degrees of correction can meaningfully reduce pain. One study found that toe separators significantly lowered pain levels by improving toe alignment and reducing pressure on the irritated joint.
Arch-supporting insoles help in a different way. Rather than correcting the toe angle directly, they redistribute pressure across the foot, taking load off the forefoot where bunion-related pain concentrates. Shoes with a wide toe box give the toes room to spread naturally and reduce friction on the bump itself.
When Surgery Becomes an Option
Surgery is typically considered when pain interferes with daily activities and conservative measures aren’t providing enough relief. The severity classification from X-rays helps determine which surgical approach fits best.
Traditional procedures involve cutting and repositioning the bone (osteotomy) to realign the joint. A newer approach called Lapiplasty addresses the problem in three dimensions, correcting the rotation and tilt of the metatarsal bone rather than just the sideways shift. With this procedure, patients can begin putting some weight on the foot within about 3 to 10 days, walk in a protective boot for the first 4 to 6 weeks, and transition back into regular shoes around the 6 to 8 week mark. Most people return to full activities, including impact sports, between 4 and 6 months after surgery.
No bunion surgery is a quick fix. Even with newer techniques, the recovery period requires patience, and there’s always some risk of the bunion returning over time, particularly if the underlying structural factors that caused it remain.