Stop Calling Them Calluses—“Fish Eyes” May Be a Viral Skin Condition

Calluses: The Skin’s Response to Pressure

A callus is an area of thickened outer skin that develops when a particular part of the body experiences repeated rubbing or pressure.

On the feet, calluses often appear beneath the heel, the ball of the foot, or other areas that bear weight.

They are common among people who walk or stand for long periods, wear poorly fitting shoes, participate in activities that create repeated friction, or have an uneven distribution of pressure across the feet.

Calluses usually have a broad area of thickened skin rather than a distinct, isolated growth. The surface may look yellowish, dry, or rough.

They are often painless, although a thick callus can become uncomfortable if pressure is concentrated in one area or if the skin develops cracks.

Calluses are not contagious because they are not caused by an infection.

Plantar Warts: A Viral Growth

A plantar wart may appear as a small, round, rough lesion surrounded by thicker skin.

The normal skin lines may stop or change direction as they cross the wart. Tiny dark dots may also be visible.

Unlike an ordinary callus, a plantar wart may be painful when squeezed from the sides. Direct pressure can hurt as well, particularly when the wart lies on a weight-bearing area.

However, these signs are not definitive. Some warts do not have obvious dark dots, and some calluses or corns can also be painful.

A professional examination is useful when the diagnosis is uncertain.

Corns: Another Condition That Can Resemble a “Fish Eye”

Corns are often confused with both calluses and plantar warts.

A corn is a small area of thickened skin that develops in response to concentrated pressure or friction. Unlike a broad callus, it usually has a more localized shape and may contain a firm central core.

Corns often appear on or between the toes, although they can develop elsewhere on the foot.

They can be painful when pressed directly because the thickened central area concentrates pressure on the underlying tissue.

Like calluses, corns are not caused by HPV and are not contagious.

A Simple Comparison

These are general clues, not a reliable method of self-diagnosis. Different lesions can overlap in appearance, and a healthcare professional may need to examine the skin closely.

3. Why Do Plantar Warts Appear?

Plantar warts develop when certain types of HPV infect the skin.

The virus can enter through tiny cuts, abrasions, cracks, or other areas where the protective skin barrier has been disrupted. These openings may be so small that a person never notices them.

After exposure, a wart may take weeks or months to become visible. Consequently, it is often difficult to identify exactly when or where the infection occurred.

Walking Barefoot in Shared Areas

Swimming pool surrounds, communal showers, changing rooms, and gym facilities are examples of places where people may encounter HPV on contaminated surfaces.

The virus can spread through contact with infected skin or contaminated surfaces, particularly when the skin is wet, softened, or damaged.

Walking barefoot in these environments can increase opportunities for exposure, although contact does not guarantee that a person will develop a wart.

Wearing flip-flops or other suitable footwear in shared wet areas is a practical precaution.

Having Cracked or Damaged Skin

Healthy, intact skin provides an important barrier against infection.

Dry, cracked heels, small cuts, and abrasions can make it easier for viruses to enter the outer layers of the skin.

People who frequently experience cracked skin should keep their feet clean, use appropriate moisturizers, and protect open areas while they heal.

Repeated Moisture and Friction

Feet can become warm and damp inside shoes, especially during exercise or in hot weather.

Prolonged moisture may soften the outer skin, while friction can create small areas of irritation or damage.

These conditions may make the skin more vulnerable to infection. However, sweating alone does not mean that someone will develop plantar warts.

Keeping feet dry and changing damp socks can help support skin health.

A Weakened Immune System

The immune system helps control HPV infections.

People whose immune systems are weakened by certain medical conditions or treatments may be more likely to develop persistent, numerous, or recurrent warts.

However, plantar warts can also occur in otherwise healthy people, including children and young adults.

Having a wart is not evidence that a person has poor hygiene or a serious underlying illness.

4. Are “Fish Eyes” Contagious?

If the growth is a plantar wart, it can spread.

HPV can be transmitted through direct contact with infected skin or through contaminated surfaces and objects. The virus may also spread from one part of a person's body to another.

For example, repeatedly picking or scratching a wart may transfer virus-containing skin material to nearby areas.

The risk of transmission varies, and not everyone who comes into contact with HPV develops a visible wart.

Can You Spread a Wart to Other Parts of Your Own Body?

Yes. This is sometimes called autoinoculation.

Scratching, biting, picking, or cutting a wart can increase the chance of spreading the virus to nearby skin. Using the same pumice stone or nail file on a wart and then on healthy skin may also transfer infected material.

Avoid manipulating the lesion, and wash your hands after touching or treating it.

Can You Get a Wart From Shoes or Towels?

Sharing footwear, socks, towels, or personal grooming tools may increase the opportunity for transmission.

This does not mean that every shared item will transmit HPV. Nevertheless, avoiding shared personal items is a sensible precaution when someone has a suspected or confirmed wart.

If you have a plantar wart, keep your feet covered in communal wet areas and follow any instructions provided by your healthcare professional.

How Long Does It Take for a Wart to Appear?

A wart may not appear immediately after exposure. It can take weeks or months before a visible lesion develops.

This delay makes it difficult to determine exactly when the infection occurred.

A newly noticed wart therefore does not necessarily indicate a recent exposure, and its presence should not be used to draw conclusions about a particular person or event.

5. How Can You Recognize a Possible Plantar Wart?

Although a professional diagnosis is preferable when there is uncertainty, several features can raise suspicion that a thickened area of skin is a plantar wart.

A Rough or Grainy Surface

Plantar warts often have an uneven, grainy, or cauliflower-like surface.

The surrounding skin may become thickened because of pressure from walking and standing.

A wart may also be partly covered by layers of hard skin, making its original appearance difficult to recognize.

Tiny Dark Dots

Small black or reddish-brown dots can sometimes be seen within the wart.

These are commonly associated with tiny blood vessels and may become more noticeable after superficial layers of skin have naturally worn away.

Do not attempt to dig into the lesion to find these dots. Cutting or probing the skin can cause bleeding, infection, and further irritation.

Pain When Walking

A plantar wart can become painful when pressure pushes it into the surrounding tissue.

Some people describe the sensation as stepping on a small stone or needle.

Pain may become more noticeable when walking barefoot or standing for long periods. However, pain alone does not distinguish a wart from a corn, callus, splinter, or other foot problem.

Changes in the Skin Lines

The natural lines on the soles of the feet may be interrupted as they cross a wart.

In a callus, these lines usually continue across the thickened skin.

This can be a useful clue, but it is not definitive, especially when the lesion is heavily thickened or irritated.

Multiple Small Lesions

Sometimes several plantar warts develop close together, creating a larger patch known as a mosaic wart.

These lesions can be difficult to distinguish from other areas of thickened skin and may require professional assessment.

If the growths are spreading, multiplying, or becoming increasingly painful, arrange a medical evaluation rather than continuing to remove layers of skin at home.

6. When Should You See a Doctor?

Not every plantar wart requires immediate medical treatment. Some disappear without intervention, particularly in children.

However, medical advice is important when the lesion is painful, persistent, unusual, or difficult to identify.

Seek an assessment if:

• The growth causes significant pain or changes how you walk.

• It grows rapidly, bleeds, develops an open sore, or changes in appearance.

• You have multiple lesions or they keep returning.

• You are unsure whether the growth is a wart, corn, callus, or another skin condition.

• Home treatment has not helped after following the product instructions.

• The surrounding skin becomes increasingly red, swollen, warm, or painful, or begins to produce pus.

• You have diabetes, poor circulation, reduced sensation in your feet, or a weakened immune system.

People with diabetes, neuropathy, or impaired circulation should not attempt to cut away thickened skin or use over-the-counter wart-removal acids without medical advice. These treatments can cause ulcers or wounds that may heal poorly.

A healthcare professional can examine the lesion and decide whether treatment is necessary. Most plantar warts can be identified by their appearance, but an unusual or persistent lesion may need further investigation.

7. How Are Plantar Warts Treated?

Treatment depends on the lesion's size, location, pain level, duration, and response to previous treatment.

There is no single treatment that works for everyone. Some warts resolve naturally, while others require repeated treatment over several weeks or longer.

Option 1: Watchful Waiting

Because many warts are harmless, it may be reasonable to monitor a small, minimally painful wart.

The immune system can sometimes control the virus without medical intervention, causing the wart to disappear.

However, spontaneous resolution may take months or even years. During this period, the wart may spread or cause discomfort.

Watchful waiting is most appropriate when the diagnosis is reasonably clear, symptoms are mild, and there are no medical factors that increase the risk of complications.

If the lesion changes, becomes painful, or starts spreading, seek advice.

Option 2: Salicylic Acid

Salicylic acid is a common ingredient in over-the-counter wart treatments.

It works by gradually softening and removing layers of thickened skin. This can help reduce the wart over time, but treatment often requires consistent application for several weeks.

For a person who is an appropriate candidate for home treatment, the general process may include:

1. Softening the wart in warm water for a few minutes.

2. Drying the skin carefully.

3. Applying the product only as directed on its packaging.

4. Protecting the surrounding healthy skin from unnecessary exposure.

5. Repeating treatment according to the product instructions.

A disposable emery board or pumice stone may sometimes be used to remove softened dead skin, but it should never be shared or used on healthy areas of the body. Do not file or scrape a lesion until it bleeds.

Salicylic acid can irritate or damage healthy skin if used incorrectly. Stop treatment and seek advice if severe irritation, significant pain, bleeding, or blistering develops.