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Why are my toenails yellow?

Yellow toenails can be caused by many things. It is not automatically a fungal toenail infection! It’s worth bearing in mind that most fungal toenail infections (onychomycosis) are caused by a pre-existing fungal SKIN infection… so if you haven’t got any signs of athlete’s foot, this means it is less likely that that yellow nail is caused by a fungus. (It’s not impossible however. I’ve written another article on this – to be posted soon).

For info - a schematic so you know which toes I'm talking about!

Common causes of yellow toenail


Either via friction from footwear, or a toe rubbing on another toe.  It is really common for the second toe to rub on the inside of the first (big) toenail. This can be anatomical (just the shape of the foot), second to deformity (e.g. in bunions, as the deformity progresses the second toe can dislocate and begin to crossover onto the big toe) OR can be caused simply by the toes being squished together by poor footwear. It is also really common for the big toe to flare up in normal walking – have a feel inside the toebox of your shoe; can you feel an indent where your big toe lies? If you can, this means your big toe is rubbing against the inside of your shoe when you are walking – causing friction on the nail plate, which will a) damage the nail causing it to thicken and b) cause the nail to lift from the nail bed – both of which can cause the nail to appear yellow.


Treatment You may benefit from wearing a gel wedge between the first and second toes, to prevent the impingement. Look at your footwear, and ensure the toebox is wide and deep enough. Also, wear a fastening – if the foot is secure in the shoe, the big toe won’t flare as much as the foot will be more stable.


Regularly moisturise thickened toenails, using e.g. a cuticle oil to gently soften the damaged nail over time to restore its elasticity and resistance to shear and friction.



Something that sets a fungal nail infection apart from other causes of a yellow toenail is that it will have an odour. A fungal toenail infection can be caused by fungus, yeasts, moulds and bacteria however the most common culprit is a fungus called trichophyton rubrum.  And she’s whiffy.

A fungal toenail infection may start as a little yellow strip down one side of the nail, that progressively spreads across the nail plate, becoming more yellow and causing the nail plate to crumble. This is where the fungus is chowing down on the proteins (keratin) in the nail.


Before you spend your hard earned dosh on pharmacy products that may or may not be needed – or even work (I’ll do a separate article on this…) I would implore you to see a podiatrist for a diagnosis. The cost of one trip to a podiatrist will save you a lot of money in treatments that won’t work in the long-run. Treatment If it’s early doors on the infection (i.e. just a small proportion of the nail is affected, and the nail plate isn’t damaged yet) try applying a little white vinegar to the nail plate twice daily. The vinegar changes the pH of the nail plate so that the fungus cannot thrive. Alternatively, try a little clotrimazole 1%.  This is marketed for fungal skin infection but is safe to use on toenails. Try this for 6 weeks, and if the infection is improving, stick with it. Keep in mind, a big toenail grows 1mm per month – and any sign of infection needs to have grown out fully before discontinuing treatment. Discontinue treatment if you notice any sensitivity or allergy to the products mentioned (e.g. a rash).

Nail Polish

If you often wear dark coloured nail polish without using a base coat, this will stain your toenails over time.  Treatment Apply a clear base coat to your nail plates before applying darker nail polishes and always give your toenail a ‘breather’; that is, for every 4-5 weeks you have nail polish on your toenails, have a week free from polish and regularly apply a cuticle oil or moisturiser to your nails over this period in order to give your nails some TLC.  Nail polish prevents that natural oil on your skin from moisturising the toenails, so they can become very dry and more prone to splitting and picking up fungal infections.



Toenails will most likely become thicker as we age, and this is a normal part of wear-and-tear.  Toenails are naturally slightly yellow in colour, and this will become more obvious as the nail thickens.


Treatment Look after your toenails early! Keep them short (in line with the edge/pulp of the toe), moisturise them so they are more resistant to shear and friction, wear footwear for function (i.e. don’t pace the streets of London in slip-on loafers, don’t do any major walking in slip-on footwear full stop!) File down thickening nails using an emery board or electronic file as a thickened toenail will continue to thicken as it is more likely to cause further damage once it is already thickened (onychauxic).



Folks with impaired venous circulation to their lower limbs will notice their toenails become yellow and crumbly over time.  This is related to poor perfusion (blood flow into tissues) and deoxygenated blood pooling in the feet. Toenails, like everything else, need a good blood supply to thrive.Circulation can also be affected on a more local level, literally restricted to the toes such as in Raynaud’s disease or phenomenon. Poor circulation in the toes is also the main contributing factor in chilblains.


Treatment If you have concerns regarding your venous circulation, speak to your doctor or a podiatrist can also help advise on this. With more local circulatory problems (Raynaud’s, chilblains) the advice is to not expose your toes to extremes of temperature. Try to always keep your feet warm by wearing e.g. two thin layers of socks, and not walking barefoot on cold surfaces such as tiles.


Smoking can cause toenails to become yellow as this causes furring of the arteries (atherosclerosis) and smaller blood vessels, which impedes the passage of healthy, oxygenated blood to the toes.


Treatment Sadly, once the nails have been damaged in this way, this cannot be undone – however vitality of the nails can be improved by regularly applying a vitamin E cuticle oil or moisturiser.


Psoriasis  (an inflammatory skin condition) can cause toenails to become yellow, thick and brittle, and for this reason is often mistaken for fungal nails. 

Treatment Psoriasis should be managed by a dermatologist, however toenails can be kept in check by regular treatment by a podiatrist to reduce the thickness of the nails. At home, this can be performed by carefully filing the nails with an emery board or e-file.  Regular application of a moisturiser or cuticle oil can help address the crumbling of the nail.


Other health conditions

Any other health condition that can affect the circulation to the feet can cause the nails to become yellow. This includes diabetes, kidney disease and lymphoedema.



This may seem daft, but I’ve occasionally seen patients who are concerned about discoloration of their toenails – and it’s been caused by the dye in their sweaty socks transferring to the toenails.

Treatment Cotton socks hold onto moisture, whereas bamboo socks are moisture-wicking and breathable. 


The discoloration will either rub away over time, or can be gently filed away using an emery board.


Nutritional Deficiences

Nutritional deficiencies can have all sorts of effects on the toenails.  Examples include iron deficiency anaemia causing pale nail beds. Blue-black discoloration of the nail plates in darker skin tones can be caused by B12 deficiency.


Treatment If a systemic (caused by something going on – or not going on - inside the body) problem is suspected for discoloration of toenails, this should be discussed with your GP or podiatrist so that blood tests can be arranged to identify the root cause.



There are lots of reasons why your toenails may be yellow! The take home message here is to consult a podiatrist who will be able to expertly examine your feet alongside taking a full medical history, in order to identify the most likely cause of the problem and commence an appropriate treatment regimen.

If you are wondering what's causing your yellow toenails, you can make an appointment to see Felicity at Oxfordshire Chiropody & Podiatry here.

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