Insoles occupy an odd place in heel pain. They are the treatment people are most willing to spend money on, and the one where spending more buys the least additional benefit. That is not an argument against using them — they are genuinely useful, and they appear in every clinical practice guideline on plantar heel pain. It is an argument for buying the right thing, in the right order.

What an insole is actually doing

The plantar fascia runs from the heel bone to the base of the toes, and it acts as a tie-rod across the arch. Every time you load the foot, the arch tries to flatten and the fascia resists it. Pain arises where that repeated tension meets the heel bone.

An insole reduces that tension in two ways. A supportive arch contour takes some of the load the fascia would otherwise carry, and a deep heel cup contains the fat pad so it cushions rather than spreading out sideways under load. That is the whole mechanism. It is a load-sharing device, not a cure, which is why the results are real but modest.

What the trials show

The most useful single study remains a randomised trial comparing sham insoles, prefabricated orthoses and custom-made orthoses in people with plantar fasciitis. Both real devices produced small short-term improvements in function compared with sham. There was no meaningful advantage for the custom devices over the prefabricated ones, and by twelve months the differences between all three groups had largely washed out.

Current clinical practice guidelines reflect that. They recommend prefabricated or custom foot orthoses for short to medium-term pain relief and functional improvement — roughly the first two weeks to four months — while being explicit that orthoses are an adjunct alongside stretching and progressive loading rather than a standalone treatment.

What to look for in a prefabricated insole

1. A deep, firm heel cup. Press the heel section. It should hold its shape rather than flatten. The cup’s job is to stop the heel pad spreading sideways as you land, which is what lets the pad do the cushioning it was designed for.
2. An arch that does not collapse under your body weight. Push your thumb hard into the arch contour. If it compresses easily in your hand it will compress completely under fifty or eighty kilograms. Soft gel arches feel pleasant in the shop and do almost nothing mechanically.
3. The right stiffness for your foot. A flexible, flat, inward-rolling foot needs a firm semi-rigid device. A rigid, high-arched foot that does not flatten usually cannot tolerate one and does better with cushioning and a contoured but softer device.
4. Full length, with a removable factory insole to replace. Take the shoe’s own insole out and put the new device in its place. Stacking one on top of the other raises your foot, tightens the shoe and changes the heel height, and is the most common fitting error.
5. Correct length and width. The arch contour has to sit under your arch. A device that is slightly too long puts its apex behind your arch and can feel worse than nothing. Trim-to-fit devices should be trimmed against the factory insole as a template.

The types, and who each one suits

When custom devices are worth the money

Trial averages describe populations, not individuals, and there is a clear set of situations where a custom device is the right call. A foot with significant structural deformity that no off-the-shelf shape will match. A meaningful leg-length difference to accommodate. Diabetes or reduced sensation, where the device is doing pressure redistribution to protect tissue rather than just easing pain. An occupational or athletic demand that has already defeated two or three well-chosen prefabs. And feet at the extremes of size or shape, where off-the-shelf geometry simply does not fit.

Outside those situations, for a straightforward first episode of plantar fasciitis, the honest answer is that a fifty-dollar insole and eight weeks of doing the loading exercises properly will outperform a four-hundred-dollar device and no exercises, every time.

Why insoles fail when they fail

• They are in the wrong shoe. A supportive device inside a shoe that folds in half and has a collapsing heel counter cannot work. Fix the shoe first.
• The factory insole is still in there. This changes the fit and the heel height and is remarkably common.
• The arch is too soft. If it compresses in your hand, it is decoration.
• They are worn only outdoors. Several hours barefoot at home every evening undoes the daytime work. This is the most frequently missed factor of all.
• They were abandoned on day three. A firm device commonly feels odd, and sometimes makes the arch ache, for the first week or two. That is expected. Sharp new pain is not.
• They were expected to do the whole job. Orthoses reduce load. They do not increase what the tissue can tolerate. Only loading does that.

How to introduce a new insole

Wear it for two to three hours on the first day and add an hour or two each day, so you reach full-day wear over about a week. Expect some arch or foot fatigue while the foot adapts to being held in a new position. If you get sharp pain, blistering, numbness, or pain somewhere new that does not settle within a couple of days, take the device out and have the fit checked rather than pushing through.

Where insoles fit in the plan

Think of it as two separate jobs. Insoles and shoes reduce the load going through the fascia, which buys comfort now. Stretching and progressive loading raise what the fascia can tolerate, which is what actually ends the episode. Doing only the first leaves you dependent on the device; doing only the second is an uphill fight. The treatment sequence sets out how they combine, and how long it takes sets realistic expectations.

Watch

Dr. Biernacki compares orthotics with shop-bought shoe inserts and explains which is right for whom.

Common questions

Do I need custom orthotics for plantar fasciitis?

Usually not, at least not first. In randomised trials custom devices performed no better than prefabricated insoles for plantar fasciitis, and the differences between both and a sham device had largely disappeared by twelve months. Custom devices earn their cost in specific situations — marked deformity, leg-length difference, reduced sensation, or repeated failure of well-chosen prefabs — rather than as a default first purchase.

How long should I give an insole before deciding it has not worked?

Six to eight weeks of consistent, full-day wear, alongside the stretching and loading work. Judge it on trend rather than on any single day: a morning spike that lasts three minutes instead of fifteen is progress even if the peak pain feels similar. Abandoning a device in the first week, which is when a firm one feels most unfamiliar, is the usual reason people conclude insoles do not help them.

Should the insole be hard or soft?

That depends on your foot and your problem. A flexible, flat, inward-rolling foot generally needs a firm semi-rigid device to control motion. A rigid high arch that does not flatten usually cannot tolerate firmness and does better with cushioning. If your main issue is a thinned heel pad rather than fascial tension, cushioning under the heel matters more than arch stiffness.

Can I wear insoles in all my shoes?

You need a shoe with a removable factory insole so the device sits at the correct depth, and enough volume that the shoe is not made tight. In practice that means buying one device per pair of regularly worn shoes, or moving a single device between two or three shoes with similar fit. Stacking a device on top of an existing insole is the most common fitting mistake.

Are the pharmacy gel insoles any good?

As cushioning, yes, and for a thinned heel pad they can help. As support, no — a gel arch that compresses in your hand offers essentially no mechanical resistance under body weight. If your problem is fascial tension, a firm supportive insole will do considerably more than a gel one at a similar price.

Will I need to wear insoles forever?

Many people do not. Once the fascia has been progressively loaded and tolerates normal activity, a good supportive shoe is often enough, and insoles become something used for long days or heavy activity. People with significant structural deformity or a high occupational load are more likely to keep using them indefinitely, which is a reasonable choice rather than a failure.

• Landorf KB, Keenan AM, Herbert RD. Effectiveness of foot orthoses to treat plantar fasciitis: a randomized trial. Archives of Internal Medicine, 2006 — the customised-versus-prefabricated comparison.
• Koc TA, et al. Heel Pain – Plantar Fasciitis: Revision 2023. Clinical Practice Guidelines, Journal of Orthopaedic & Sports Physical Therapy.
• Martin RL, Davenport TE, Reischl SF, et al. Heel pain — plantar fasciitis: revision 2014. Journal of Orthopaedic & Sports Physical Therapy, 2014.
• American Academy of Orthopaedic Surgeons, OrthoInfo. Heel Pain.
• Schwartz R, et al. Plantar Heel Pain. StatPearls, NCBI Bookshelf.

Related heel pain guides

• Best shoes for plantar fasciitis
• Plantar fasciitis treatment
• Plantar fasciitis exercises and stretches
• Plantar fasciitis
• Heel fat pad atrophy
• Product guides
• Heel pain: how to work out what you have
• Heel pain in pregnancy