Plantar fasciitis accounts for the majority of heel pain cases in adults, but the heel is a surprisingly complex structure, and pain there can come from a half-dozen different sources depending on where exactly it hurts, what makes it worse, and who you are. Pain under the heel, behind the heel, on the inner side, or deep within the bone each point to different problems with different causes and different solutions. What follows is a walk through the most common culprits, the less obvious ones that get missed, and the factors that make some people more vulnerable than others.
Plantar Fasciitis and Why It Dominates the List
The plantar fascia is a thick band of tissue that runs along the bottom of the foot from the heel bone to the toes. When it becomes irritated and begins to degenerate, the result is a sharp, stabbing pain right under the heel, usually worst with the first steps in the morning or after sitting for a long time. This condition affects both athletes and non-athletes and is one of the leading reasons people visit a doctor for foot pain.1PubMed Central. Plantar Fasciitis Pathophysiology and the Potential Role of Mesenchymal Stem Cell-Derived Extracellular Vesicles as Therapy
The name “fasciitis” suggests inflammation, but the reality is more nuanced. Early stages do involve inflammation, but chronic cases show something closer to tissue degeneration, where the fibers of the fascia break down over time rather than staying in a continually inflamed state. This distinction matters for treatment: anti-inflammatory drugs help early on, but long-standing cases often need approaches that promote tissue repair rather than simply reducing swelling.
The classic presentation is unmistakable. You step out of bed, put your foot on the floor, and feel a stabbing pain under your heel that eases after a few minutes of walking. It tends to flare up again after long periods of rest or at the end of a day spent on your feet. If this sounds familiar, you are almost certainly dealing with plantar fasciitis. But “almost certainly” is not “definitely,” and several other conditions mimic this pattern closely enough to fool patients and clinicians alike.
The Heel Spur Myth
For decades, the bony growth on the underside of the heel bone, visible on X-rays, was blamed for causing heel pain. Many people are still told they have a “heel spur” as if that explains everything. The evidence tells a different story. A high rate of calcaneal spurs occur without causing any pain at all, which strongly suggests the spur itself is not the sole source of the problem.2PubMed Central. Plantar Fasciitis With a Calcaneal Spur
That does not mean heel spurs are completely irrelevant. A study of over a thousand feet found that spurs and thickened plantar fascia frequently coexist, and people with heel pain were roughly twice as likely to have both features together compared to people without pain. But here is the interesting part: tenderness when pressing on the heel was not specifically associated with the spur or the thickened fascia, either alone or in combination, in people who had heel pain.3Rheumatology. Coexistence of plantar calcaneal spurs and plantar fascial thickening in individuals with plantar heel pain The spur, in other words, is more likely a consequence of long-term mechanical stress rather than the cause of your pain. It is a marker that your heel has been under strain, not the reason it hurts.
This matters practically because some people are told they need surgery to remove the spur, when the real issue is the soft tissue around it. If you have been diagnosed with a heel spur and told it is the source of your pain, it is worth asking whether the plantar fascia or surrounding structures are the actual problem.
Pain at the Back of the Heel
Not all heel pain lives on the underside. Pain at the back of the heel, right where a shoe’s counter presses against the ankle, usually involves the Achilles tendon or the structures around it. Haglund’s deformity is an abnormal bony enlargement on the upper back part of the heel bone, right where the Achilles tendon attaches. This bump can irritate the bursa (a small fluid-filled sac) between the bone and the tendon, leading to a condition sometimes called “pump bump” because rigid shoe backs tend to aggravate it.4PubMed Central. Haglund’s Deformity, Retrocalcaneal Bursitis, and Achilles Tendinopathy (Haglund’s Syndrome) Treated with Arthroscopic Calcaneoplasty, Synovectomy and PRP Injection Outcome Score: A Case Report
When the bony bump, inflamed bursa, and tendon irritation all occur together, the combination is called Haglund’s syndrome. The pain feels different from plantar fasciitis: it is at the back of the heel rather than underneath, worsens when you push off while walking or running, and the area often becomes visibly swollen or red. Shoes with rigid backs make it worse, and switching to open-backed shoes or those with softer counters can offer immediate relief.
Achilles tendinopathy on its own, without the bony bump, is another common cause of posterior heel pain, especially in runners and people who suddenly increase their activity level. The tendon gradually breaks down from repetitive strain, producing a dull ache that sharpens with activity. It often involves the part of the tendon right at or just above the heel bone insertion.
When the Heel’s Natural Cushion Wears Out
Under the heel bone sits a specialized fat pad that acts as a shock absorber for every step you take. After about age 40, this pad begins to thin out as it loses water, collagen, and elastic tissue, reducing its ability to protect the bone from impact.5Annals of Rehabilitation Medicine. Clinical Characteristics of the Causes of Plantar Heel Pain The result is a deep, bruise-like pain directly under the center of the heel that worsens with barefoot walking on hard surfaces.
Fat pad atrophy gets confused with plantar fasciitis all the time, and the distinction matters because the treatments differ. Plantar fasciitis pain is usually sharpest at the front edge of the heel and worst first thing in the morning. Fat pad pain is more diffuse, centered directly under the heel bone, and tends to worsen throughout the day as you accumulate impact. Cushioned insoles and heel cups that mimic the fat pad’s shock-absorbing role are the main intervention. Stretching the plantar fascia, which helps fasciitis, does little for a worn-out fat pad.
Nerve Problems That Mimic Plantar Fasciitis
Two nerve-related conditions are worth knowing about because both are frequently mistaken for plantar fasciitis, leading to treatment that does not work.
Tarsal tunnel syndrome occurs when the posterior tibial nerve gets compressed as it passes through a narrow space on the inner side of the ankle. The symptoms include pain, numbness, tingling, and weakness in the heel and sole of the foot.6PubMed Central. Tarsal Tunnel Syndrome – A Comprehensive Review The tingling and burning quality of the pain is the key distinction from fasciitis. Tapping the nerve behind the inner ankle bone can reproduce the symptoms, a test your doctor can perform in the office.
Baxter’s nerve entrapment is even trickier. This involves compression of a small nerve branch on the inner side of the heel, and it produces chronic, burning pain in exactly the same area where plantar fasciitis hurts. Because the location overlaps so closely, it is frequently misdiagnosed as fasciitis. The clue is that Baxter’s nerve pain tends to have a burning or electric quality and may come with numbness, which pure fasciitis typically does not produce.7PubMed. Baxter’s nerve: the hidden culprit of chronic heel pain If you have been treated for plantar fasciitis for months without improvement, a nerve problem should be on the list of suspects.
Stress Fractures of the Heel Bone
The calcaneus, or heel bone, bears enormous forces with every step, and repetitive stress can produce tiny cracks in the bone that cause significant pain. Calcaneal stress fractures usually result from overuse, particularly in runners, military recruits, and anyone who dramatically increases their weight-bearing activity over a short period.8PubMed Central. Calcaneus and Traumatic Stress Fracture
Diagnosis can be tricky because the symptoms overlap with other common causes of heel pain, and standard X-rays often look normal early on. The pain tends to be more diffuse than fasciitis, hurts with squeezing the heel from both sides (a test called the “squeeze test”), and does not follow the classic morning-pain pattern. MRI is usually needed to confirm the fracture.9PubMed Central. Delayed Diagnosis of Calcaneal Stress Fracture: A Case Report Getting this diagnosis right matters because a stress fracture requires rest and possibly immobilization, while continuing to exercise through it risks a complete fracture.
Systemic Inflammatory Diseases
Sometimes heel pain is not a local mechanical problem but a sign of a body-wide inflammatory condition. Psoriatic arthritis and ankylosing spondylitis (a type of inflammatory spinal arthritis) both commonly attack entheses, the spots where tendons and ligaments attach to bone. The Achilles tendon insertion at the back of the heel is one of the most frequently affected sites. In one MRI-based study of patients with these conditions, Achilles enthesitis was present in a large percentage of cases, making the heel one of the most common locations for inflammation.10Annals of the Rheumatic Diseases. Enthesitis in patients with psoriatic arthritis, axial spondyloarthritis and healthy subjects assessed by ‘head-to-toe’ whole-body MRI and clinical examination
The red flags for an inflammatory cause are heel pain that worsens with rest rather than activity (the opposite of a stress fracture), morning stiffness lasting more than 30 minutes, pain that improves with movement, and heel pain accompanied by other symptoms like low back pain, skin rashes, or eye inflammation. If you are under 40 and have heel pain that gets worse when you sit still, it is worth asking your doctor to look beyond the usual mechanical explanations. Imaging with MRI can reveal inflammation at the tendon insertion that would not show up on an X-ray or ultrasound.11PubMed Central. Magnetic resonance imaging characteristics in patients with spondyloarthritis and clinical diagnosis of heel enthesitis: post hoc analysis from the phase 3 ACHILLES trial
Why Some People Are More Vulnerable
Heel pain is not random. Several measurable risk factors increase the odds of developing chronic plantar heel pain. A case-control study found that people with the condition were roughly three times more likely to be obese and nearly four times more likely to have pronated (flat) feet compared to matched controls without heel pain.12PubMed Central. Obesity and pronated foot type may increase the risk of chronic plantar heel pain: a matched case-control study
Higher body weight increases the load on the heel with every step, and pronated feet change the angle at which force travels through the plantar fascia. These two factors are the most consistently supported in the research. Other contributors include occupations that require prolonged standing on hard surfaces, tight calf muscles that increase strain on the plantar fascia, and sudden changes in activity level. Age plays a role as well, both through the fat pad thinning described earlier and through the general wear and tear on connective tissue.
Footwear is another factor with real-world data behind it. In a survey of people who regularly wore hard-heeled shoes, over 40% reported footwear-related discomfort, and prolonged use for five to eight hours was associated with the most severe pain episodes.13European Journal of Clinical Pharmacy. IMPACT OF HARD-HEEL FOOTWEAR ON PLANTAR FASCIITIS Shoes that lack cushioning or arch support force the heel to absorb more impact than it is designed to handle on its own, especially on concrete and tile floors.
Heel Pain in Children
Children and teenagers get heel pain too, but the cause is almost always different from what adults experience. Sever’s disease, or calcaneal apophysitis, is the primary cause of heel pain in children between roughly 8 and 15 years old.14Advanced Emergency Nursing Journal. Sever’s Disease (Calcaneal Apophysitis) It occurs when the growth plate at the back of the heel bone becomes irritated from repetitive stress during a period of rapid growth.
Active children who play running and jumping sports are the typical patients. The pain is at the back of the heel, worsens with activity, and improves with rest. Despite the name, Sever’s disease is not really a disease. It is a self-limiting growth-related condition that resolves once the growth plate fuses, usually by the mid-teens. It is also considered underreported, meaning many cases get dismissed as “growing pains” without a proper diagnosis.15PubMed Central. Sever’s Disease of the Pediatric Population: Clinical, Pathologic, and Therapeutic Considerations In the meantime, heel cups, activity modification, and calf stretching are the standard approaches.
How Heel Pain Gets Diagnosed
Most heel pain is diagnosed clinically, meaning a doctor can figure it out by asking where it hurts, when it hurts, and pressing on specific spots. But when the diagnosis is unclear or treatment is not working, imaging enters the picture. Ultrasound has become the go-to first-line imaging tool for heel pain because it is fast, inexpensive, and does not involve radiation. One comparative study found that ultrasound with a newer technique called shear wave elastography achieved over 93% accuracy for identifying plantar fasciitis and nearly 98% accuracy for Achilles tendinopathy.16PubMed Central. Ultrasound imaging and shear wave elastography for the differential diagnosis of heel pain: a comparative cross-sectional study
Standard ultrasound on its own has diagnostic accuracy comparable to MRI for plantar fasciitis, making it a practical first step.17International Journal of Rheumatic Diseases. High‐resolution ultrasonographic diagnosis of plantar fasciitis: a correlation of ultrasound and magnetic resonance imaging MRI is reserved for cases where the diagnosis remains uncertain, where nerve entrapment or a stress fracture is suspected, or when complex pathology needs to be ruled out. Plain X-rays are useful for spotting bone spurs, fractures, and tumors but cannot visualize soft tissue very well.
Treatment Approaches That Work
The good news about plantar fasciitis, by far the most common cause, is that most cases resolve with conservative treatment over several months. The first-line approach includes stretching the calf and plantar fascia, wearing supportive shoes with cushioned insoles, and avoiding activities that aggravate the pain. Over-the-counter anti-inflammatory medication can help in the early stages.
When these measures are not enough, two interventions have solid evidence behind them. Extracorporeal shock wave therapy, which delivers focused sound waves to the affected area, reduces pain intensity and improves daily function in people with chronic plantar fasciitis.18PubMed Central. Long Term Effectiveness of ESWT in Plantar Fasciitis in Amateur Runners Custom foot orthotics are another well-supported option. One head-to-head study found that both shock wave therapy and custom orthotics improved pain, foot function, and foot health, with no clear winner in the short or medium term. Over the long term, however, custom orthotics showed a slight edge in sustaining improvements.19PubMed Central. Comparison of extracorporeal shock wave therapy with custom foot orthotics in plantar fasciitis treatment: A prospective randomized one-year follow-up study
For the stubborn minority of cases that resist all conservative treatment, surgery is an option. In a study of patients who had exhausted nonsurgical treatments, 84% were satisfied with their surgical outcome, and half reported being completely pain-free afterward. But about one in ten saw no improvement at all, which underscores why surgery is a last resort.20PubMed Central. Surgery for Patients With Recalcitrant Plantar Fasciitis: Good Results at Short-, Medium-, and Long-term Follow-up
Why Human Heels Are Built for Trouble
There is a deeper reason heel pain is so common in humans, and it has to do with how we evolved to walk. Humans are heel-strikers: when we walk, our heel hits the ground first, and our body weight rolls forward over the foot. This gait pattern turns out to be an evolutionary trade-off. Research comparing human and chimpanzee walking mechanics found that heel-striking generates high impact forces and loading rates through the heel, but it also lowers the energetic cost of walking by a substantial margin. Humans who walk on the balls of their feet first spend 26 to 41% more energy than heel-strikers.21PubMed Central. Heel-strike mechanics reveal evolutionary trade-offs in hominin bipedalism
In short, our bodies chose efficiency over durability. Heel-striking saves energy, which was an enormous advantage for early humans covering long distances, but the trade-off is that the heel absorbs punishing impact forces thousands of times per day. Add modern hard surfaces, excess body weight, and decades of use, and it is easy to see why the heel is one of the most complaint-prone structures in the body.
Rare Causes Worth Knowing About
In uncommon cases, heel pain can signal something more serious. Primary tumors of the calcaneus are rare, but when they do occur, heel pain and localized swelling are the most common symptoms. Because clinicians are not used to seeing tumors in this location, delays in diagnosis can happen, sometimes with serious consequences.22PubMed Central. Primary tumours of the calcaneus This is not a reason to panic about ordinary heel pain, but it is a reason to follow up if your heel pain does not fit any of the usual patterns, does not respond to standard treatment, is accompanied by unexplained swelling, involves night pain that wakes you from sleep, or is associated with unintentional weight loss. These features should prompt your doctor to consider imaging beyond a standard X-ray.
Infections of the heel bone (osteomyelitis) are another rare cause, more common in people with diabetes or compromised immune systems. And certain metabolic conditions, including gout, can produce sudden, intense heel pain when uric acid crystals deposit in the plantar fascia or the Achilles tendon attachment. The onset of gout is typically dramatic and rapid, distinguishing it from the gradual buildup of most other heel conditions.