Thick, yellow or crumbly toenails can be a sign of a fungal nail infection (onychomycosis), although other nail conditions can look similar. Fungal nail infections are common and notoriously slow to clear, but treatment can be effective — and good foot hygiene and suitable footwear can help reduce the conditions in which fungus thrives.
Treatment depends on how much of the nail is affected and how severe the infection is. Antifungal nail treatments may be suitable for some infections, while more persistent or extensive cases may need assessment by a pharmacist, GP or podiatrist and, in some cases, prescription antifungal tablets.
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This guide explains what fungal nail infections look like, what can cause them, the treatment options available and how your shoes and socks can help protect sore or thickened nails while you’re dealing with one.
I’ve dealt with a fungal nail infection myself, so I can tell you firsthand: the hardest part isn’t finding a treatment, it’s sticking with one for long enough to actually work. Nails grow slowly, and clearing an infection properly takes consistent treatment over months, not days — there’s no shortcut, whatever the internet tries to tell you.
And on that note, I’ll be blunt: there’s a lot of nonsense floating around online about “miracle” home remedies — Vicks VapoRub being one of the most repeated. I’d steer well clear. At best these things do nothing at all while your infection quietly gets worse; at worst they delay you starting a treatment that might actually work. Save yourself the months of wasted hope and go with something genuinely designed for the job.
What I’d Actually Look For
Worth knowing before you buy: not every “fungal nail treatment” on the shelf actually contains an antifungal ingredient — some work purely by changing the nail’s environment, which isn’t the same thing. If you want a genuine medicated treatment, look for one containing Amorolfine, a recognised antifungal used in products like Schollmed’s Once Weekly treatment. A once-a-week application is also, frankly, easier to actually stick with over several months than something you’re supposed to remember daily — and given consistency is the real challenge here, that matters more than people realise.
Check Schollmed Once Weekly Fungal Nail Treatment on Amazon
📌 At a Glance
Here’s everything I know about fungal nail infections — the causes, what actually treats them, and how to stop them coming back.
If you’d rather skip straight to specific questions, jump to the Q&A below.
What Is a Fungal Nail Infection?
Onychomycosis is a fungal infection of the nail plate and nail bed, most often caused by dermatophytes (the same family that causes athlete’s foot). It typically starts at the nail edge and creeps inward, making nails thick, discoloured, and brittle.
If your foot pain isn’t limited to this one condition, our Complete Guide to Foot Pain Relief walks you through all the main causes, treatments, and footwear tips to keep every step more comfortable.
Causes and Risk Factors
- Untreated or recurrent athlete’s foot spreading to the nails
- Warm, damp shoe environments (sweaty feet, non-breathable footwear)
- Nail trauma from tight toe boxes or long nails hitting the shoe
- Ageing, diabetes, poor circulation, or reduced immunity
- Walking barefoot in communal areas (pools, locker rooms)
Symptoms and How to Recognise Them
- Yellow, brown, or white discolouration starting at the edge
- Nail thickening, crumbling, or flaky debris under the nail (subungual debris)
- Nail shape distortion, lifting from the nail bed (onycholysis)
- Mild odour; sometimes discomfort in shoes due to nail bulk
Why Footwear Matters
Keeping feet dry and reducing pressure around an affected nail can make footwear more comfortable and may help reduce some of the conditions in which fungi thrive. Tight shoes can also put additional pressure on a thickened or damaged nail.
References
- NHS – Fungal nail infection overview
- NICE CKS – Fungal nail infection: Prevalence
- Sigurgeirsson B, et al. (2020). Prevalence of onychomycosis in the general population: A systematic review. J Eur Acad Dermatol Venereol
Fungal Toe Nail Treatment Options
At-home & over-the-counter
- Antifungal nail treatments – medicated nail lacquers or solutions are available from pharmacies. Follow the instructions carefully because fungal nail treatment usually needs to be continued for months.
- Keep the nail trimmed – keeping an affected nail short can make it easier to manage, but don’t aggressively file, scrape or dig underneath it. If a nail is very thick or difficult to cut, a podiatrist can help.
- Treat athlete’s foot at the same time – if you also have athlete’s foot, treating the skin infection can help reduce the chance of fungus spreading or returning.
- Keep feet and footwear dry – change damp socks, allow shoes to dry between wears and follow any advice supplied with antifungal products you’re using.
Prescription options (talk to your clinician)
- If pharmacy treatment hasn’t worked, the infection is severe or several nails are affected, a GP may take a nail sample before considering antifungal tablets. Tablets such as terbinafine may be prescribed when appropriate, but they aren’t suitable for everyone and can interact with other medicines, so this needs to be assessed by a clinician.
What results to expect
Toenails grow slowly, so even successful treatment takes time to become obvious. The healthier nail grows out from the base, and it can take a year or longer for a big toenail to grow out completely.
Prevention & Hygiene Tips
- Treat athlete’s foot promptly to protect nails
- Change socks daily (twice if sweaty); use moisture‑wicking fabrics
- Give footwear time to dry – Avoid repeatedly wearing damp or sweaty shoes. Alternating pairs can give footwear more time to dry thoroughly between wears.
- Keep nails short (not too short) and filed smooth to reduce shoe impact
- Wear flip‑flops in communal showers/pools; don’t share nail tools
- Disinfect nail clippers/files; consider separate tools for affected nails
Best Footwear for Fungal Nails
If a fungal nail has become thick or tender, the right footwear won’t cure the infection, but it can make the affected toe considerably more comfortable while treatment does its job.
Look for:
- Enough width and toe-box height so the affected nail isn’t pressing against the shoe.
- A roomy toe shape that doesn’t squeeze the toes together.
- Breathable uppers where practical, particularly if your feet tend to become hot or sweaty.
- Socks that keep your feet comfortable and manage moisture well.
- Adjustable fastenings if swelling or nail tenderness makes the fit vary.
If the shoe feels wide enough but the top of a thickened nail still rubs against it, you may actually need more toe-box depth rather than more width. My guide to high-volume toe boxes explains the difference.
When to See a Doctor or Podiatrist
- It’s worth getting professional advice if:
- You’re not sure it’s a fungal infection. Nail injury, psoriasis and other nail conditions can sometimes look similar.
- Several nails are affected, the nail is painful, badly thickened or difficult to manage yourself.
- The skin around the nail becomes painful, red or swollen, particularly if you think there may be another infection.
- Pharmacy treatment hasn’t helped despite using it correctly for the recommended length of time.
- You have diabetes, poor circulation or a weakened immune system. In these circumstances, seek professional advice rather than treating a troublesome nail entirely yourself.
Fungal nail infections can sometimes occur alongside or follow athlete’s foot, so it’s worth checking the skin between your toes and around your feet as well.
FAQs
Q: Do I need antifungal tablets or can I use a nail treatment?
A: Some fungal nail infections can be treated with antifungal nail treatments from a pharmacy, but these can take many months to work. If the infection is severe, several nails are affected or pharmacy treatment hasn’t worked, speak to a GP. Antifungal tablets may be considered if they’re suitable for you.
Q: Can I wear nail polish?
A: Check the instructions for any antifungal nail treatment you’re using, as ordinary nail polish may not be recommended alongside some medicated lacquers. Cosmetic polish can also make it harder to see how the affected nail is changing as it grows out.
Q: Can shoes cause a fungal nail infection to come back?
A: Damp, sweaty footwear can provide conditions in which fungi thrive. Allow shoes to dry properly between wears, change damp socks and treat any athlete’s foot at the same time to help reduce the risk of the infection returning.
Q: How long does a fungal toenail infection take to clear?
A: Fungal nail infections take time to treat, and the damaged part of the nail doesn’t suddenly return to normal. Instead, healthier-looking nail gradually grows out from the base. A big toenail can take a year or longer to grow out completely, so improvement is usually measured in months rather than weeks.
I had a fungal infection affecting my big toenail. Following ankle surgery in January 2025, I noticed that the nail began to improve even though I hadn’t been treating the fungal infection myself.
When I left hospital, my foot and ankle were still heavily stained from the povidone-iodine antiseptic used before surgery. I later discovered that iodine has recognised antimicrobial properties, including activity against some fungi, which made me wonder whether that had played a part.
I can’t know whether the iodine was responsible for the improvement — it may simply have been coincidence — and I wouldn’t recommend using surgical antiseptic as a DIY fungal nail treatment. But it was an interesting change to observe after having the infection for some time.