Yellow Toenails

Written By: Chloe Wilson BSc(Hons) Physiotherapy
Reviewed By: FPE Medical Review Board

Yellow Toenails: Common causes and treatment options for yellow toenails

Yellow toenails are a common problem with a variety of possible causes. Changes in toenail colour usually develop gradually over time.

They may also be associated with hardening and thickening of the nail, which may also become brittle and prone to breakage.

Yellow toenails may be from something simple such as nail polish, a fungal infection or in some cases may be a sign of a serious underlying medical condition which requires attention. But how can you tell the difference? 

Common Causes Of Yellow Toenails

Let's have a look at the most common causes of yellow toe nails, what causes them and what other symptoms may be associated with them to help you work out what is going on and what you can do to treat them. 

1. Fungal Nail Infections

The most common cause of yellow toenails is a fungal infection that attacks the nail, known as onychomycosis. It is often ignored initially as there is little if any discomfort, but the longer it is left untreated, the longer it will take to clear when treatment does finally begin.

Fungal infections tend to be located underneath the nail, and gradually eat away at the keratin, the protein that makes nails hard and strong. Fungal toenail infections can also be linked with yeast infections elsewhere in the body.

The type of infection tends to vary depending on the climate you live in – in cool, temperate climates it is typically due to dermatophytes, whereas in hot, humid, tropical environments it tends to be from non-dermatophylic moulds or candida. 

Symptoms Of Fungal Nail Infections

Fungal nail infections often result in thick, yellow toenails

The first sign of a fungal nail infection is the gradual discoloration of the toenails starting at the edge of the nail and spreading inwards.

The nails gradually thicken, become brittle and may even break and in some instances there may be a foul smell from the infection.

There may also be some pain or discomfort when pressure is placed on the nails or when wearing shoes. Typically it is the big and little toes that are most affected by fungal nail infections.

Causes of Fungal Yellow Toenails

Fungus thrives in moist, warm, damp conditions so fungal toenail infections are often picked up from walking barefoot in public places such as swimming pools, public showers and gyms. Common causes of fungal nail infections include:

  • Footwear: tight, ill-fitting shoes and socks that don’t let your feet breathe or place repetitive pressure on the toes
  • Sweating: excessive sweating increases moisture
  • Environment: living or working in a humid or damp environment
  • Skin Conditions: such as psoriasis
  • Medical Conditions: such as diabetes or peripheral vascular disease
  • Injury: damage to the nail or surrounding skin
  • Age: increased risk with aging 

Yellow toenails from fungal infections are fairly common with approximately 10% of the adult population suffering from onychomycosis. 

Treatment For Fungal Infections

Treatment should be started as promptly as possible, so don’t ignore yellow toenails, hoping they will just sort themselves out. Treatment usually involves using one or more of the following: 

Anti-fungal gel can help to treat fungal nail infections, a common cause of thick, yellow toenails
  • Topical Treatment: usually in the form of a gel or polish that you apply directly to yellow toenails twice a day until the infection has cleared completely – this can take six to twelve months
  • Oral Antifungal Medication: such as Lamisil. This tends to be more effective than the polish, but may not be appropriate if you have other health conditions
  • Toenail Removal: this may be done surgically or with chemicals. It may take up to twelve months for the nail to fully regrow
  • Laser Therapy: photodynamic laser therapy can be used to treat the nail fungus
  • Home Remedies: are often a popular treatment for yellow toe nails, such as tea tree oil or a vinegar foot soak, but there is little scientific evidence for their efficacy

Fungal nail infections are highly contagious so do keep those yellow toenails covered!

2. Yellow Nail Syndrome

Yellow Nail Syndrome is a rare, but serious cause of yellow toenails. There are three typical characteristics with this syndrome: 

Yellow nail syndrome is a serious cause of yellow toenails and is usually accompanied by respiratory problems and lymphodema
  • Yellow Nails: Nails are slow to grow, thickened and discoloured a yellow/green colour. There may be ridges across the nails as well as increased curvature and in some cases the nail detaches from the nail bed

  • Lymphedema: Swelling of the limbs due to fluid retention, which most commonly affects both legs but in some cases may also affect the arms and face. About 80% of people with yellow nail syndrome will develop lymphedema, and in around one third of cases it is the first sign of the condition

  • Lung Problems: Many people with this syndrome will experience respiratory problems such shortness of breath and coughing. Around a half of those with yellow nail syndrome will suffer from recurrent chest infections or bronchiectasis, a chronic lung condition where the airways become damaged and excess mucus is produced. Pleural effusions (excess fluid in the space surrounding the lungs) affect around 40% of people with yellow nail syndrome

People who present with at least two of these three symptoms are usually diagnosed with yellow nail syndrome. Yellow toenails/fingernails are usually always seen in this condition but the colour changes may be quite subtle. Treatment usually focuses on addressing any lymphedema or respiratory issues. Vitamin E may be given to help reduce nail discoloration.

If you suspect you may have yellow nail syndrome, you should seek prompt medical advice.

3. Nail Polish Stains

Frequent use of nail polish, particularly dark colours can lead to nail discolouration

Repetitive painting of your nails can lead to discoloration - this is a common but not serious cause of yellow finger and toe nails. Many brands of nail polish contain iron oxide which over time can absorb into the nail resulting in yellow toenails. This is particularly common when using red, orange or darker shades of nail polish.

Applying a clear base coat before applying polish can help reduce staining. Frequent use of nail polish can also trap moisture under the nail bed which may lead to infection and therefore nail discoloration. 

The simplest way to treat discolouration caused by nail polish is to leave the nails un-painted for a couple of weeks and they should return to their normal colour. When you do then want to repaint them, always apply a base coat and avoid reds and oranges, opting instead for lighter colours.

4. Jaundice

Yellowing of the skin is the classic feature of jaundice but yellow toenails are often seen with it as well. Jaundice is a medical condition where a problem with the liver causes high levels of bilirubin, resulting in yellowing of the skin, eyes, mouth and nails.

It would be extremely unusual for the only symptom to be yellow toenails, so if you have no other symptoms, you are unlikely to be suffering from jaundice. However, if you have noticed a yellow/green tinge to your skin or in the white your eyes, or have noticed your urine is darker or your faeces lighter than usual, you should consult your doctor.

Other Causes of Yellow Toenails

Other possible, less common, causes of yellow toenails include:

1. Psoriasis

Psoriasis is a chronic autoimmune disease causing patches of red, flaky skin covered with silver coloured scales. It is sometime associated with nail discolouration, typically yellow, brown or green and it may look like there is a drop of oil underneath the nail. You can find out more about nail psoriasis here.

Paronychia is a bacterial infection that causes redness and swelling around a nail, with the nail itself become thick and yellow

2. Paronychia

This is a bacterial infection in the nail or surrounding skin that results in redness, inflammation and pus around the edge of the nail, and thickening and discoloration of the nails. It may affect the fingernails or toenails.

3. Diabetes

Type 2 diabetes is often accompanied by poor circulation and nerve damage in the feet which can lead to yellowing or blackening of the toenails. Good foot care is vital for anyone suffering from this condition, so if you have developed yellow toenails and are diabetic, consult your doctor promptly.

What Else Can Help?

In many cases, yellow toenails also become thickened and may change shape. If this is the case, have a look at the thick toenails section to find out what is going on.

If you are also suffering from pain in your toes and none of these are sounding like your condition, visit the toe pain diagnosis section for help working out what may be wrong.

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Page Last Updated: 09/29/22
Next Review Due: 09/29/24