A lump on the side of the foot is a common problem and can be quite worrying, but in most cases, it’s nothing serious.
There are lots of different things that can cause lumps and bumps on the side of the foot.
There may be a problem with one of the foot bones, a build-up of fluid, inflammation from over-use or a benign growth.
It is very uncommon for a foot lump to be cancerous but any new growth should always be evaluated by your doctor.
Here we are going to look at the different causes of a lump on the side of the foot and how to identify which one you have. We will then go on to look at the best ways to treat them. If you are more bothered by pain than swelling, check out the Side Foot Pain article.
A lump on the side of the foot may be caused by:
Each of these causes of a side of foot lump will present slightly differently and require different treatment. So let’s start by looking at the nine most common causes of lumps on the side of the foot and then we’ll go on to look at the more unusual ones.
The most common cause of a hard lump on the side of the foot is a bunion. Bunions can occur at the:
With a hallux valgus, the big toe shifts out of position, slowly deviating towards the second toe. As the tip of the toe moves inwards, the base of the big toe shifts outwards causing a hard bump on the side of the foot. If you have a lump on your big toe, chances are it’s a bunion!
With a Tailor’s Bunion, the tip of the little toe shifts inwards towards the fourth toe and the base of the little toe shifts outwards, resulting in a hard lump on the outside of the foot. If you have a lump by your little toe, it’s most likely a bunionette!
Over time, as the toe shifts over further, the side of foot lump becomes more prominent and may start to rub on your shoe.
Common symptoms of foot bunions are:
Bunions are typically caused by wearing tight, narrow shoes, particularly if they have a high heel. There is also thought to be a genetic link so if someone in your family has bunions, you are more likely to develop one.
The sooner you start treating a bunion lump on the side of the foot, the better as the deviation gets harder to correct the greater it is.
You can find out more about this common cause of side of foot lumps and how to treat them in the Foot Bunions section.
Another common cause of a lump on the side of the foot is a ganglion cyst.
Ganglion cysts are small, fluid-filled pockets that form just below the skin. They can occur anywhere in the foot but are most common on the side or top of the foot.
What causes ganglion cysts to form is unknown but they are thought to be linked to repetitive micro-injuries (from friction or pressure) and arthritis. Ganglia are three times more common in women than men and are most common between the ages of 20-50.
A ganglion lump on the side of the foot is usually round or oval and can vary in size. Typically they are fairly small (pea-sized) but they can grow much larger. Ganglion foot lumps are usually soft but firm to touch rather than hard.
A lump on the side of the foot from a ganglion is not normally painful unless it starts to rub on your shoes or press on one of the surrounding nerves which can cause some tingling in your foot.
Painless ganglion lumps on the foot don’t need to be treated and may go away on their own over time. However, if the ganglion becomes painful or affects foot movement or daily activities such as walking, then treatment such as medication, splinting, aspiration or occasionally surgery may be recommended.
A bump on the side of the foot may be due to tendonitis – inflammation of one of the foot tendons. There tends to be more of a general swelling than a specific lump with tendonitis.
Tendonitis usually develops due to repetitive overuse, altered foot biomechanics, or an injury e.g. ankle sprain.
In the early stages of foot tendonitis, there is typically a sharp or burning pain where the tendon attaches to the foot bone, which is worse during activity. Over time, you may notice a soft bump on the side of the foot where the tendon has started to thicken.
Common types of tendonitis that can cause a lump on the side of the foot are:
There are lots of treatment options for foot tendonitis including ice, exercises and orthotics. You can find out more about how to treat a tendonitis bump on the side of the foot in the Foot Tendonitis section.
Another possible cause of a painful lump on the side of the foot is a fracture or break in one of the bones. The most common fractures to cause side foot bumps are:
Treatment for foot fractures will vary depending on the type, severity and location of the fracture but will usually include a combination of PRICE (protect, rest, ice, compression & elevation), medication and exercises. Surgery is only needed if there is significant pain, deformity or displacement of the bone.
You can find out more about the common causes, symptoms, treatment and prevention options in the Foot Fractures section.
A lump in the arch of the foot may be due to a plantar fibroma. A plantar fibroma is a benign (non-cancerous) growth where one or more nodules form around the plantar fascia.
Plantar fibromas are usually small (less than 1 inch) forming a firm bump in the arch of the foot. They may form in isolation or in clusters.
Plantar fibromas are twice as common in men as women and are thought to be linked to genetics. They are usually only painful when there is direct pressure through the fibroma foot lump.
There are a number of different options with treatment for plantar fibromas including injections, exercises, orthotics and surgery.
Plantar fibromas are the most common cause of a lump in the arch of the foot and you can find out more about the causes, symptoms, diagnosis and treatment options in the plantar fibromatosis section.
If you have lots of small lumps on the side of your foot around your heel, chances are they are piezogenic papules.
Piezogenic papules are soft, skin-coloured bumps that affect people who spend long periods on their feet, or people with connective tissue disorders e.g. Ehlers-Danlos syndrome.
Piezogenic papules develop when fatty tissue herniates through the dermis (inner layer of the skin) into the connective tissue around the heel, resulting in small bumps on the side of the foot.
They rarely cause any symptoms and are usually left untreated. Occasionally, piezogenic papules may press on nearby blood vessels or nerves in which case they can be treated with rest, orthotics, acupuncture, injections or occasionally surgery.
Another common cause of a lump on the big toe that is painful, red and swollen is foot gout. Gout is caused by a build-up of uric acid crystals that collect in the big toe joint. Symptoms usually develop rapidly, often at night and can lead to intense pain in the big toe.
Uric acid is a natural product produced by the body when it breaks down certain chemicals, but problems arise when the kidneys aren’t able to filter it out quick enough. This leads to the formation of hard, spiky crystals in joints. Gout can affect any joint in the body but most commonly affects the big toe.
Recurrent bouts of gout are common without correct treatment and, over time, can lead to the formation of tophi - large, visible lumps of urate crystals that develop under the skin.
A hard lump inside the arch of the foot may be caused by an accessory navicular.
An accessory navicular is a congenital abnormality (meaning its present from birth) where there is an extra piece of bone or cartilage found in the medial foot arch.
The medical terms for an accessory navicular are an os navicularum or os tibiale externum.
In most cases, an accessory navicular goes completely unnoticed, not causing any symptoms. However, following an injury (e.g. ankle sprain), or chronic irritation (from repetitive friction or excessive activity) an accessory navicular can result in:
Asymptomatic cases of accessory naviculars don’t require any treatment. If however, the accessory lump on the side of your foot becomes painful, it can be treated with a combination of immobilization, ice, medication, physical therapy and orthotics. In severe cases, the accessory navicular may need to be surgically removed, however this is rare.
Skin lumps on the side of the foot are usually caused by corns or calluses.
Corns and calluses typically develop in response to repetitive friction or pressure on the skin e.g. from ill-fitting footwear.
There are lots of different treatment options for corn and callus lumps on the side of the foot including creams, chemicals, pumice stones and medications.
You can find out lots more about the causes, diagnosis and best treatment options in the Foot Corns & Calluses section.
There are a few other less common causes of lumps on the side of the foot:
There are lots of possible causes of foot lumps.
Lumps that can occur anywhere on the side of the foot may be caused by ganglion cysts, stress fractures, bursitis, lipoma, sebaceous cysts, rheumatoid nodules or cancer.
Treatment will depend on what is causing the lump on the side of your foot and you can find out more about the best treatment options by using the links above.
Page Last Updated: 09/20/22
Next Review Due: 09/20/24