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?
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.
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.
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.
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:
Yellow toenails from fungal infections are fairly common with approximately 10% of the adult population suffering from onychomycosis.
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:
Fungal nail infections are highly contagious so do keep those yellow toenails covered!
Yellow Nail Syndrome is a rare, but serious cause of yellow toenails. There are three typical characteristics with this 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.
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.
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 possible, less common, causes of yellow toenails include:
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.
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.
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.
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.
Page Last Updated: 09/29/22
Next Review Due: 09/29/24