A toenail that turns yellow, thickens or crumbles may have a fungal infection. The NHS says these infections are not serious but can take a long time to treat. Antifungal nail medicine from a pharmacy needs to be used for 6 to 12 months, and it may take several months before you see an improvement. The infection is cured when healthy nail grows back at the base. See a GP if it’s severe and treatment hasn’t worked, it has spread to other nails, you have diabetes, or you have a weakened immune system. This sets out the NHS page “Fungal nail infection”.
1. Not serious, but slow. Brush-on medicine for 6 to 12 months; several months before you see a change.
2. It’s cured when healthy nail grows back at the base, the NHS says.
3. Treatment not working, spreading, diabetes or weakened immunity: see a GP — tablets for up to 6 months, with blood tests to check the liver.
Symptoms — NHS
The NHS says nails may become brittle, discoloured or thicker than usual. It usually affects toenails but can affect fingernails, and often starts at the edge and spreads across the nail, turning it white or yellow. The nail may crumble or lift off, and the skin around it can be swollen and painful.
From a pharmacy — NHS
| Type | What the NHS says | Worth noting (ours) |
|---|---|---|
| When | If the nail’s look bothers you or it’s painful, see a pharmacist | — |
| What | An antifungal nail medicine you brush on | — |
| How long | Daily or weekly depending on the product, for 6 to 12 months | Several months before you see an improvement |
| Caution | May not be suitable under 18, or if pregnant or breastfeeding | — |
| When it’s cured | Healthy nail grows back at the base | So the discoloured part won’t vanish at once (our reading) |
The NHS says to treat athlete’s foot quickly so it doesn’t spread to the nails. The NHS thresholds for athlete’s foot are in athlete’s foot.
When to see a GP — NHS
| If | Where | Worth noting (ours) |
|---|---|---|
| The infection is severe and treatment hasn’t worked | GP | — |
| It has spread to other nails | GP | — |
| You have diabetes | GP | Foot problems can be more serious |
| You have a weakened immune system, for example after a transplant or during chemotherapy | GP | — |
Treatment from a GP — NHS
| Item | What the NHS says | Worth noting (ours) |
|---|---|---|
| Tablets | Antifungal tablets if pharmacy treatments haven’t worked | A nail sample may be taken to find the type |
| How long | Up to 6 months | — |
| Blood tests | To check the liver, before and during treatment | — |
| Side effects | Headaches, an itchy rash, stomach ache, feeling sick, diarrhoea | — |
| Not suitable | Some conditions such as liver or kidney disease; pregnancy or breastfeeding | — |
| Nail removal | For badly infected nails, a minor procedure under local anaesthetic | — |
Prevention — NHS
The NHS says you’re more likely to get it if your feet are constantly warm and damp, or you wear trainers for long periods and have hot, sweaty feet.
| Type | What the NHS says | Worth noting (ours) |
|---|---|---|
| Do | Treat athlete’s foot quickly | To stop it spreading to the nails |
| Do | Keep nails short; keep feet clean and dry | — |
| Do | Wear clean socks every day | — |
| Do | Wear flip-flops in gym or pool showers | — |
| Do | Wear well-fitting shoes (avoid high heels and narrow toes); throw out old shoes | — |
| Don’t | Wear shoes that make your feet hot and sweaty | — |
| Don’t | Share towels, wear other people’s shoes, or share nail clippers or scissors | — |
Checklist
- ☐ Brush-on medicine for 6 to 12 months; give it several months
- ☐ Watch for healthy nail growing at the base
- ☐ Treat athlete’s foot quickly
- ☐ Dry feet, clean socks daily, flip-flops in showers
- ☐ Not working, spreading, diabetes or weakened immunity: GP
Questions that remain
I’ve used it for a month and nothing has changed.
The NHS says the medicine needs 6 to 12 months and it may take several months before you see an improvement. Look for healthy nail growing at the base.
The nail is digging into the skin.
The NHS thresholds for that are in ingrown toenail.
Sources
- NHS — Fungal nail infection — source (page shows: reviewed 27 March 2024, next review 27 March 2027; checked 19 October 2026). Symptoms, pharmacy treatment and timing, 4 GP reasons, GP treatment (tablets, blood tests, side effects, nail removal), who gets it, 7 dos and 4 don’ts.
- Not read. Korean agency guidance on fungal nail infections; Korean product classifications.
- What we added. The “worth noting” column and the Korean care gloss.
Where else to check
- A pharmacy or dermatology clinic — choosing a brush-on medicine, or if it isn’t working.
Written on 19 October 2026. The content is from the NHS; the glosses are ours.
