If only one of your feet hurts, it is natural to wonder why, because you walk on both of them every day. In my experience, one-sided foot pain is rarely random. It almost always suggests that one foot is being loaded more than the other, and the useful question is not which foot hurts, but why that foot is taking more than its share. Here is how I work through it with patients, roughly in the order the questions come up.
Why would only one foot hurt when I use both the same way?
The first thing that comes to my mind is whether you have been putting more load through that foot, or whether there is some underlying asymmetry in your foot posture or alignment that makes you load that side more.
That is the theme running through almost every case of one-sided pain. Your two feet may look similar, but the way force travels through them during standing, walking, and sport is not necessarily equal. Find the reason one side is doing more work, and you are usually most of the way to the cause of the pain.
The first thing I check is how you load that foot
I start with what you actually do. Your daily activity, and your habits when you stand and walk, tell me a great deal. If you play badminton or tennis, I will want to know your dominant hand, because that tells me which leg you tend to pivot and push off from. The foot that plants and drives repeatedly takes more load, session after session.
Everyday habits matter just as much as sport. The way you stand at work, the leg you always lead with, and how you carry weight through the day all add up over time on one side.
I also check for a strength difference between the two legs. If one lower limb is weaker than the other, that side, or the side working harder to compensate for it, can end up overloaded, and that one-sided weakness can itself be the source of the pain.
Old injuries count, on either foot
Next I look for old injuries, and this works both ways.
An old fracture or previous lower-limb surgery, even on the other leg, can make you lean your weight onto the uninjured side. This happens during the rehabilitation period and can carry forward subconsciously even when you have already recovered. Over time, that steady extra load on the good foot creates the very pain you are now feeling. We call that compensatory loading, and it is why the painful foot is often not the one with the history.
An old injury can also make the same foot more vulnerable and more likely to be hurt again. For example, if you have pain in the posterior tibial tendon on the inside of the ankle, and a history of an ankle ligament tear on that side, the two are often linked. The loss of structural integrity at the ankle throws more stress onto the posterior tibial tendon, and that tendon pays the price.
Sometimes the reason is higher up
If the foot itself does not explain it, I look further up the leg. A leg length discrepancy, whether structural from a genuine difference in bone length, or driven by something like scoliosis in the spine, changes how load is shared between the two sides.
Most people assume the longer leg must be the one that suffers. That is not true. A shorter leg can take more impact, because the centre of pressure shifts across to the shorter side during the loading phase of your gait, and that side absorbs more force.
Knee alignment can do the same. If one knee is more bow-legged or more knock-kneed than the other, that difference alone can explain why pain shows up in just one foot. This is exactly the kind of thing a gait and biomechanical assessment is designed to pick up.
When one-sided foot pain is a red flag
Most one-sided pain is mechanical, but not all of it, and a few situations need attention straight away rather than watching and waiting.
The biggest red flag is redness, swelling and warmth over one foot or leg, especially if you have diabetes, heart disease, high cholesterol, or are older. That combination can point to a skin infection such as cellulitis, or to a deep vein thrombosis, both of which are emergencies.
It is rare, but I have had a patient come in with sudden, excruciating pain in one leg, only for me to find a blocked artery, an acute limb ischaemia, and send her straight to A&E for emergency treatment to restore the blood flow. If you have pain like that, or the redness, warmth and swelling above, do not wait for an appointment. Seek medical attention immediately.
Does which foot it is help the diagnosis?
On its own, the side that hurts rarely gives me the diagnosis. What genuinely helps is comparing the painful foot against the painless one, because that establishes your baseline.
Some patterns do point somewhere. Pain over the inner ankle together with an arch that has visibly collapsed on the painful side, and not the other, paints a fairly clear picture of a posterior tibial tendon problem. Gout tends to strike one foot, often a single joint, whereas rheumatoid arthritis or the nerve pain of diabetes usually affects both feet. Most conditions are not that tidy, though, which is why comparing against the pain-free side tells me more than the side alone ever could.
What I check when only one foot hurts
When I assess the painful foot, I first work out which structure is involved, then compare it with the painless side to be sure the other one is genuinely fine. I load that structure with clinical tests, sometimes a resistance strength test, to see whether the pain reproduces. After that, I look at your gait and compare how each side moves.
The comparison matters at every step. Nobody’s feet are perfectly symmetrical, so the healthy side gives me a reference for what is normal for you. In plantar fasciitis, for instance, an ultrasound scan can compare the thickness of the plantar fascia on both sides, which helps confirm the diagnosis and shows me how far the painful side has drifted from your own baseline. Where the cause is an uneven load, redistributing that load, sometimes with custom foot orthoses, is part of settling it.
What you should do if only one foot hurts
Whether it is one foot or both, any foot pain that lasts more than two weeks is worth having checked. If you notice redness, swelling, warmth or unexplained bruising, get it seen sooner rather than later.
The worst mistake I see is delay. People push through, quietly compensating on the other leg, and by the time they come in they have two painful feet instead of one, which makes recovery slower and more tedious than it needed to be. One-sided pain is your body pointing at an imbalance, and it is far easier to sort out early.
If only one of your feet has been hurting and it is not settling, book a consultation with any of our podiatrists at any of our three clinics in Singapore. Bringing both feet to the assessment, not just the sore one, is exactly how we find out why.
