Pain on the inside of your heel most often comes from plantar fasciitis, a condition where the thick band of tissue running along the bottom of your foot develops tiny tears where it attaches to your heel bone. It affects roughly 10% of the population at some point, and for about half of those with severe cases, the pain can linger for years. But plantar fasciitis isn’t the only possibility. Several other conditions target the same spot, and telling them apart matters because the fix is different for each one.
Plantar Fasciitis: The Most Common Cause
The plantar fascia is a tough band of connective tissue that runs from your heel to your toes, supporting the arch of your foot. It anchors to a small bony bump on the inner side of your heel bone called the medial calcaneal tuberosity. Every time you take a step, that attachment point absorbs force. Over time, repetitive stress creates microtears at the junction between the fascia and the bone, and the tissue degenerates faster than it can repair itself.
The hallmark symptom is a sharp or stabbing pain on the inner bottom of your heel, worst with your first steps in the morning or after sitting for a long time. The pain often eases once you’ve been walking for a few minutes as the tissue warms up, then returns after prolonged standing or activity. If you pull your toes back toward your shin, stretching the bottom of your foot, you’ll likely feel it intensify. That response is one of the key ways clinicians identify it.
Most people recover within several months using conservative measures: icing, consistent calf and plantar fascia stretching, supportive footwear, and scaling back activities that aggravate it. If things haven’t improved after a few months of steady effort, options like injections, shock wave therapy, or (rarely) surgery come into play.
Nerve Compression in the Ankle
Tarsal tunnel syndrome is essentially the foot’s version of carpal tunnel syndrome. A nerve called the tibial nerve runs through a narrow passageway on the inner side of your ankle, formed by bone and ligaments. When that tunnel gets compressed from swelling, a cyst, flat feet, or an ankle injury, the nerve fires pain signals into your inner heel and the bottom of your foot.
The key difference from plantar fasciitis is the quality of the pain. Nerve compression tends to produce burning, tingling, numbness, or a “pins and needles” sensation rather than the sharp, focused ache of fascia damage. You might also notice weakness in your foot muscles. Tapping along the inside of your ankle can reproduce the symptoms, a test known as a Tinel sign. If your heel pain comes with any of those nerve-type sensations, this diagnosis is worth investigating.
Tendon Strain Along the Inner Foot
Your posterior tibial tendon runs from a muscle deep in your calf, passes behind the bony bump on the inside of your ankle, and attaches to the bones that form your arch. It’s the primary tendon responsible for holding your arch up. When it becomes inflamed or starts to degenerate, you feel pain and tenderness along the inside of your foot and ankle, often extending toward the inner heel.
This condition tends to develop gradually, especially in people over 40 or those who spend a lot of time on their feet. The pain is typically worse with activity, particularly walking, climbing stairs, or standing on your toes. Left untreated, the tendon can weaken to the point where your arch starts to flatten, which shifts the pain pattern and creates new problems up the chain in your knees and hips. Early intervention with supportive shoes or orthotics and targeted strengthening exercises can prevent that progression.
Stress Fracture of the Heel Bone
A calcaneal stress fracture is a small crack in the heel bone itself, usually from a sudden increase in activity (ramping up running mileage, starting a new exercise program, or spending long hours on hard surfaces). The pain builds gradually over days to weeks, often starting as a dull ache that you can push through before becoming sharp enough to limit walking.
One way to suspect a stress fracture over soft tissue problems: squeeze both sides of your heel with your hands, like you’re pressing it between your palms. If that squeeze produces pain, it points toward a bone issue rather than fascia or tendon damage. Plantar fasciitis pain, by contrast, is reproduced by pressing directly into the bottom of the heel. Stress fractures need rest, sometimes a walking boot, and typically 6 to 8 weeks to heal.
Why Flat Feet Make It Worse
Overpronation, where your foot rolls too far inward with each step, is a common thread connecting many of these conditions. When your arch collapses excessively, the foot loses its natural shock-absorbing ability. Impact forces increase, and those forces get directed straight into the structures on the inner side of the heel: the plantar fascia attachment, the posterior tibial tendon, and the tibial nerve pathway.
The increased strain doesn’t stay in your foot, either. Your ankle, knee, and hip joints have to compensate for the misalignment, which is why people with chronic heel pain sometimes develop problems further up the leg. Supportive footwear, over-the-counter arch supports, or custom orthotics can reduce the inward roll and take pressure off the medial heel. For many people, this single change provides significant relief regardless of the specific diagnosis.
How to Tell These Conditions Apart
The location and character of your pain offer the strongest clues:
- Sharp pain directly under the inner heel, worst with first morning steps: plantar fasciitis is the most likely cause. Pulling your toes upward will reproduce it.
- Burning, tingling, or numbness spreading from the inner ankle into the heel: tarsal tunnel syndrome. Tapping the inside of your ankle may trigger the sensation.
- Aching along the inner ankle and arch, worse with activity: posterior tibial tendon strain, especially if standing on your toes is painful or difficult.
- Deep heel ache that worsens over weeks, painful when you squeeze the sides of the heel: calcaneal stress fracture.
These conditions can also overlap. Someone with flat feet might develop plantar fasciitis and posterior tibial tendon problems simultaneously. If your pain doesn’t fit neatly into one pattern, or if you’re noticing symptoms from multiple categories, imaging or a hands-on exam can sort it out.
Signs That Need Prompt Attention
Most inner heel pain responds well to rest, ice, stretching, and better shoes. But certain symptoms signal something more urgent. Seek immediate care if you have severe heel pain right after an injury, significant swelling near the heel, inability to bend your foot downward or walk normally, or heel pain accompanied by fever and numbness or tingling. Schedule a visit if your pain persists even when you’re not on your feet, or if it lasts more than a few weeks despite consistent home treatment.