Fungal Infections
Red Flags — beyond the simple ringworm
| Red flag | Why it matters | Action |
|---|---|---|
| Recurrent/widespread fungal infection — undiagnosed diabetes or immunosuppression/HIV | The fungal infection is a symptom of a treatable systemic condition. | Check HbA1c; consider immunosuppression/HIV testing; treat the cause |
| Steroid-modified tinea (tinea incognito) | Misdiagnosis perpetuates and worsens infection. | Stop steroid; skin scrapings; treat as fungal |
| Tinea capitis / kerion | Scarring alopecia if untreated; needs oral therapy & contact treatment. | Hair/scalp samples + oral antifungal; treat contacts; prompt treatment of kerion |
| Athlete's foot as a portal for cellulitis | Recurrent leg cellulitis, especially with oedema/diabetes. | Treat tinea pedis; foot/skin care; treat cellulitis if present |
| Changing / ulcerating / non-healing "fungal" lesion | Skin cancer or alternative diagnosis mislabelled as fungal. | Reconsider diagnosis; dermatology referral/biopsy; don't treat blindly |
| New or changing pigmented streak in a "fungal" nail, or a lesion growing under the nail | Subungual melanoma can masquerade as a dystrophic nail; Hutchinson's sign (pigment spreading onto the nail fold) is a late clue. | Urgent dermatology assessment for possible nail-unit melanoma (NG12 has no nail-specific criterion) — do not send clippings and wait |
| Infected fissure, ulcer or spreading redness on the foot of someone with diabetes | The diabetic foot can deteriorate quickly; antifungal cream alone is not the treatment. | Diabetic-foot pathway (NICE NG19); same day if limb- or life-threatening |
| Extensive groin/buttock/trunk tinea failing terbinafine, especially with South Asia travel or family links | Possible terbinafine-resistant Trichophyton indotineae (UKHSA 2025 notification). | Scrapings with the suspicion stated; dermatology advice; do not simply repeat terbinafine |
| Before oral antifungals — drug interactions / hepatotoxicity | Terbinafine/itraconazole carry interactions and liver risk. | Confirm diagnosis; review interactions; baseline/monitor LFTs per guidance |
🔬 Why confirm first
Explain the rationale for sampling before oral tablets.
"The nail tablets work, but they're a long course and can affect the liver, so it's worth a quick nail clipping to be sure it's a fungus first — about half of dodgy-looking nails turn out not to be."💉 The diabetes conversation
Connect recurrence to the bigger picture sensitively.
"These infections sometimes keep coming back when blood sugar's running high — and with the thirst and tiredness you've mentioned, I'd really like to check for diabetes. Sorting that out would help your skin too."🦶 Treat the source
Explain athlete's foot feeding the rest.
"The athlete's foot is likely the source that's spread to your groin and nails — so treating your feet properly, keeping them dry, and not sharing towels stops it coming back."🚫 Undoing the steroid
Explain why the steroid cream made it worse.
"That steroid cream calmed the itch but actually fed the fungus and spread it — so we'll stop it and use an antifungal instead."🙈 Embarrassment and the groin
Patients often under-report groin symptoms, and nail disease makes people hide their feet — avoiding sandals, swimming, or intimacy. Normalising the problem helps them show you the whole picture, including the groin and a partner's symptoms.
"This is really common and nothing to be embarrassed about — it's the same fungus as athlete's foot. Is anyone at home, or your partner, getting anything similar? If so, it's worth treating everyone at once."⏳ Realistic timescales
People expect nails to look normal when the tablets finish. Toenails grow slowly, so a cured nail can take a year or more to look clear. Setting this expectation early prevents "the tablets didn't work" and requests for repeat courses.
"If the tablets work, you'll see clear, healthy nail growing up from the base over the months — the old damaged part only goes when it's cut away, so for toenails it can be a year or more before they look normal."- Prescribing oral antifungals for nails without confirmation
- Missing the underlying diabetes/immunosuppression
- Not recognising steroid-modified tinea
- Treating the rash but not the source (feet)/hygiene
Soon / same day
Don't delay- Cellulitis (from tinea pedis)Treat infection; manage the fungal portal
- Kerion / extensive tinea capitisPrompt oral treatment; avoid scarring
- Immunosuppressed / severe / unwellInvestigate; consider specialist
Sample first
Before orals- OnychomycosisNail clippings → terbinafine if confirmed
- Tinea capitisHair/scalp samples → oral + contacts
- Diagnostic doubt / treatment failureScrapings; reconsider mimic
Topical
First-line- Tinea corporis/cruris/pedisTopical antifungal + hygiene
- Candidal intertrigo / genitalTopical/oral azole; address moisture
- Pityriasis versicolorTopical antifungal; counsel re pigment
- Starting orals without confirmation
- Missing cellulitis/kerion/immunosuppression
- Not examining the feet (source) when treating groin/nails
- Mislabelling eczema/psoriasis/erythrasma as tinea
"I want to get you on them — but the nail tablets are a long course and occasionally affect the liver, and not every odd-looking nail is actually fungal. A quick clipping confirms it, so we don't put you through months of medication for nothing. And while we wait, I'll check a blood test for diabetes, because that's often why these infections keep coming back — sorting it would help your skin and your health overall."
- Oral antifungals without confirmation/LFTs/interaction check
- Not checking HbA1c in recurrent fungal disease with diabetic symptoms
🚩 Treat the rash, find the cause, confirm the orals
Gary's formulation is multi-site dermatophyte infection (tinea pedis spreading to cruris and nails) with steroid-modification of the groin lesion, very likely on a background of undiagnosed diabetes (thirst, weight change, fatigue, family history). The plan: confirm the nails before oral terbinafine, stop the steroid and treat as fungal, treat the feet as the source with hygiene advice, and check HbA1c — treating the person and the cause, not just the visible rash.
- Naming the rash without seeking the underlying cause
- Missing steroid-modified tinea / a mimic
- Not acting on newly-found diabetes
- Not referring a non-resolving/suspicious lesion
Validate — name the expectation and the reason behind it
Gary has done his reading, the nails embarrass him, and oral terbinafine is the treatment most likely to clear a confirmed dermatophyte toenail infection. His request is sensible. Say so first, before any "but" — otherwise the sample and blood tests sound like obstacles.
"You're right that tablets are the treatment most likely to clear toenails like yours — creams alone rarely get through a thick nail. I can see these really bother you, and I want to get you on the right treatment."Explain — why confirmation and bloods come first
Several things make a thick, discoloured nail look fungal when it isn't: psoriasis, old injury, pressure from footwear, and occasionally a yeast or mould that terbinafine treats poorly. The BAD onychomycosis guideline (2014) advises confirming the diagnosis mycologically — clippings for microscopy and culture — before starting treatment. The course is months long and needs a baseline liver test. Gary's thirst, tiredness and weight change also need an HbA1c, and that result may change the rest of the plan.
"Not every nail that looks like this is actually a fungus, and the tablets are a three-month-plus course that can occasionally upset the liver. So I'd like a clipping to prove it's fungal, and a liver blood test before we start. While we're taking blood, I'd like to check your sugar level too, because of the thirst and tiredness."Negotiate — something today, the tablets on a named date
Gary leaves with active treatment for the skin (antifungal cream for feet and groin, steroid stopped), practical foot care, the clipping taken, bloods booked, and a date to go through results. If microscopy is positive and LFTs are normal, terbinafine can start then — he does not need to wait weeks for the culture, as positive microscopy supports treatment.
"Today you'll start a cream for the feet and groin, and I'll take the nail clipping now. Once the clipping shows fungus and your liver test is fine — usually within a week or two — we'll start the tablets. Does that feel like a fair plan?"Macerated, moist web spaces let dermatophytes (and bacteria) multiply and create fissures. Drying removes the moisture the fungus needs and helps fissures heal, closing the portal for cellulitis.
Dry carefully between the toes after washing — a separate towel for the feet, or a hairdryer on a cool setting. Apply the antifungal cream to the web spaces and soles, not just the itchiest spot. Treat both feet even if one looks worse.
Shoes and socks hold infected skin scales and stay damp. Wearing the same pair every day re-seeds the feet after treatment — a common reason for "failed" treatment.
Cotton or moisture-wicking socks changed daily; alternate shoes so each pair dries for 24–48 hours; breathable footwear where work allows; antifungal powder in shoes; flip-flops in communal showers, gyms and pool changing rooms.
Tinea cruris is usually carried from the feet to the groin on fingers, towels and underwear. Drying the groin before the feet, and putting socks on before underwear, reduces transfer.
Don't share towels; wash towels, bedding and underwear regularly at a hot wash if the fabric allows; loose cotton underwear; avoid scratching and then touching other sites. Ask about a partner or household members with similar symptoms and treat at the same time.
Topical steroids suppress the local immune response, so the fungus spreads while the redness fades — tinea incognito. Potent steroid–antifungal combination creams (common in products bought abroad or online) are also linked to the spread of resistant T. indotineae.
Bring all creams to the review. If the patch is very inflamed, only a hydrocortisone 1%–imidazole combination for up to 7 days, then antifungal alone (Canesten HC SmPC). Warn that itch may flare briefly after stopping the steroid.
Hyperglycaemia impairs neutrophil function and skin barrier repair, and diabetes is a recognised risk factor for tinea pedis, onychomycosis and candida. Weight and skin folds add moisture and friction in the groin.
If the HbA1c confirms diabetes: structured education, diet and activity, and medicines per NICE NG28, with individualised targets agreed. Weight loss reduces intertrigo. Check that the patient knows diabetes can cause recurrent skin, genital and foot infections.
Fungal fissures, thick nails and reduced sensation combine to put the diabetic foot at risk of ulcers and infection. Thickened nails can also press on the nail bed and cause subungual ulceration.
If diabetes is confirmed, perform and record a foot risk assessment and give foot-care education. Nail thinning/debridement by podiatry helps symptoms and improves topical penetration, and is often the better option for frail, older people in whom oral courses carry more risk.
In a child with tinea capitis, T. tonsurans spreads between people (siblings, school), and asymptomatic carriers can reinfect a treated child. Microsporum canis comes from cats and dogs.
Examine household contacts and consider sampling; antifungal shampoo (ketoconazole 2% or selenium sulfide) for the child and household to reduce spore shedding; don't share combs, brushes or hats; vet review for pets if Microsporum is grown (BAD tinea capitis 2014). UKHSA: stay away from school until treatment has started, then attend as normal.
- Diagnosis confirmed — positive microscopy or culture for nail disease; samples taken for scalp (treat without waiting in children)
- Liver — ask about liver disease and alcohol; baseline LFTs before terbinafine (SmPC; SPC)
- Heart — any heart failure or ventricular dysfunction rules out itraconazole for onychomycosis (SmPC; SPC)
- Interactions and pregnancy — full drug list including OTC; itraconazole with simvastatin is contraindicated (MHRA DSU Aug 2012); pregnancy status and contraception, especially for griseofulvin
- Only hydrocortisone 1% with an imidazole (e.g. miconazole or clotrimazole), only for an intensely inflamed patch, only for up to 7 days, then antifungal alone (Canesten HC SmPC)
- Never a steroid alone on a possible fungal rash
- Avoid potent steroid combinations (clobetasone, betamethasone, clobetasol mixes) — they cause tinea incognito and are linked to resistant T. indotineae
- If a patient has used one, record which product, for how long, and send scrapings if the rash is extensive
"Put the cream on the rash and a couple of centimetres of normal skin around it, including between all the toes. Keep going for a week or two after it looks clear — stopping early is the main reason it comes back."
SCA phrase: "Creams work well for skin — and I'll treat your feet as well as the groin, because the feet are usually where it starts."
"This one has a mild steroid to calm the itch — use it for no more than a week, then carry on with the plain antifungal cream."
SCA phrase: "The steroid on its own hid the fungus and let it spread. If we use a steroid at all, it's a mild one mixed with an antifungal, for a few days only."
"Take one tablet a day for the full course, even when the nail doesn't look better yet. Stop and call us the same day if you notice yellow skin or eyes, dark urine, pale stools, itching all over, constant sickness or tummy pain, or a blistering rash. Some people lose their sense of taste — tell us if that happens."
SCA phrase: "Once the clipping confirms fungus and your liver test is normal, we'll start terbinafine — one tablet a day for about three months, with a check on your liver along the way."
"Take the capsules with a meal. Stop and contact us if you become breathless, your ankles swell or you gain weight quickly, or if you get yellowing of the skin. Tell any doctor or pharmacist you're on it before starting any new medicine."
SCA phrase: "This alternative is effective but affects many other medicines and isn't safe with heart failure, so I'd like to check your heart history and all your tablets first."
"Give it with a fatty food such as milk or yoghurt — it absorbs better. Older teenagers: women must avoid pregnancy during treatment and for a month afterwards, and men must not father a child during treatment and for six months afterwards (SPC)."
SCA phrase (parent): "Scalp ringworm needs medicine by mouth — creams can't reach the hair roots. Your child can keep going to school once treatment has started."
"File the affected nail, clean it with the swab, then paint the lacquer on once or twice a week. It's slow — think in months — and works best when only the tip of the nail is affected."
SCA phrase: "If you'd rather avoid tablets, nail paints rarely clear it and aren't routinely prescribed here — leaving it, or podiatry to thin the nails, are reasonable choices."
"If this keeps coming back, it's worth checking your sugar level — high sugar feeds thrush."
SCA phrase: "Thrush that keeps coming back is a signal — I'd like to check a blood test for diabetes."
Work and Footwear
Safety boots, long shifts on foot, hot kitchens and manual jobs keep feet warm and wet. Advice that ignores the working day won't be followed. Tinea itself does not need time off work, and people with athlete's foot can keep working and exercising with simple precautions.
"What are your feet in all day? If it's boots, a second pair to swap each day and a change of socks at lunchtime will do more than you'd think."Driving and DVLA — if diabetes is diagnosed
Fungal infection has no driving implications. A new diabetes diagnosis might: Group 1 drivers managed by diet or by medicines with a low hypoglycaemia risk (e.g. metformin) do not usually need to tell the DVLA. Insulin or sulfonylureas bring hypoglycaemia rules, and Group 2 (lorry/bus) licence holders have stricter notification rules — check current DVLA guidance.
"If the test shows diabetes, most people starting with diet or metformin don't need to tell the DVLA — but if you drive for work, or we ever need tablets that can drop your sugar, we'll go through the rules together."Partner, Intimacy and Household
Groin tinea and genital candida cause embarrassment and can affect intimacy; a partner may have the same rash. Tinea spreads through close contact and shared towels. It is not a sexually transmitted infection, but framing it plainly avoids blame and gets everyone treated.
"This isn't something you've caught from being unclean and it isn't an STI — it's the athlete's foot fungus. If your partner has an itchy patch, it's worth them getting a cream too so you don't pass it back and forth."Identity, Appearance and Avoidance
People with thick, discoloured nails often avoid sandals, swimming, the beach or bare feet in front of others. This is a real impact on quality of life. It justifies treatment when the diagnosis is confirmed and the patient chooses it, as long as the expected timescale is realistic.
"It sounds like the nails stop you doing things you'd enjoy. That's a good reason to treat them — as long as you know that the nail takes many months to grow out looking normal."Children, School and Stigma (Scalp Ringworm)
Parents worry about hair loss, other parents' reactions and school. UKHSA guidance is that a child with ringworm stays away only until treatment has started. Explain that it is common, treatable, and not a sign of poor hygiene.
"Scalp ringworm is common in children and isn't about cleanliness. Once the medicine has started, they can go to school as normal — we'll check brothers and sisters, and pets, too."Taking in a Diabetes Diagnosis
Gary came in about his nails and may leave with a possible diabetes diagnosis — and his father had it. People often link diabetes with a parent's complications. Name that possibility, pace the information, and book a proper conversation when the result is back.
"I know you came about your nails, and I don't want to overload you. If the test shows diabetes, we'll sit down properly to talk it through — it's very different now from when your dad was diagnosed, and catching it early makes a real difference."Day 0 — Today
Stop the steroid. Start a topical antifungal for feet and groin (imidazole for the groin if candida is possible). Take nail clippings as far back as possible, with subungual debris, and groin scrapings because the rash was steroid-modified. Bloods: HbA1c and baseline LFTs. Foot-hygiene advice. Safety-net for cellulitis and a changing lesion.
1–2 Weeks — Results Review
Microscopy is usually back within days; culture takes weeks. Positive microscopy with normal LFTs and no interaction or contraindication → start oral terbinafine. HbA1c ≥48 mmol/mol with symptoms → diagnose diabetes and begin management per NICE NG28 (repeat if asymptomatic or borderline). Check the skin is responding to topical treatment. Negative mycology with high suspicion → repeat the sample properly rather than treating blind.
4–6 Weeks — Safety and Skin Check
Periodic LFTs on terbinafine as the SmPC suggests; ask about taste change, rash and hepatitis symptoms. Groin and feet should be clear — continue the imidazole for 1–2 weeks after clearance. Not clear → check adherence, reconsider the diagnosis (erythrasma, psoriasis, eczema), and think of T. indotineae if extensive. Diabetes: foot risk assessment and education.
3–4 Months — End of the Oral Course
Toenail course is 12–16 weeks (BAD onychomycosis 2014; SPC). Look for clear, healthy proximal nail growth. The damaged distal nail will still look abnormal. A second course is not needed just because of how the nail looks at this point. Reinforce foot hygiene and treatment of any tinea pedis relapse.
12–18 Months — Outcome and Annual Diabetes Review
Toenail should have grown out. Persistent or recurrent disease → repeat mycology; consider an alternative drug, podiatry or dermatology. If diabetic: annual review including foot risk assessment (NICE NG19) and HbA1c per NG28.
Memory rule — the "LHIP" check before and during oral antifungals
Liver (baseline LFTs for terbinafine; symptoms at every contact) · Heart (no itraconazole for nails with heart failure) · Interactions (itraconazole/fluconazole CYP3A4; terbinafine CYP2D6; griseofulvin enzyme induction) · Pregnancy (avoid orals; griseofulvin contraception 1 month women / 6 months men). Then judge cure by mycology and proximal nail growth, not appearance at the end of the course.
| What | Test / check | When | Action threshold |
|---|---|---|---|
| Oral terbinafine | LFTs; hepatitis symptoms; taste; rash | Baseline; periodically (SmPC suggests after 4–6 weeks); any symptoms | Stop if significant LFT rise (interpret clinically), jaundice, dark urine, pale stools, persistent nausea, or blistering/mucosal rash. Yellow Card. |
| Itraconazole | Heart-failure symptoms; LFTs if symptomatic/long course; interactions | Before starting; each contact; whenever a new drug is added | Stop if breathlessness, oedema or rapid weight gain; hepatitis symptoms → stop and check LFTs. |
| Griseofulvin | Pregnancy status; contraception | Before and during treatment | Stop and seek advice if pregnancy occurs. |
| Topical course | Clinical response | End of course | Not better → adherence, scrapings, reconsider diagnosis, consider T. indotineae. |
| Onychomycosis cure | Clear proximal nail growth; repeat mycology if doubt | End of course; 12–18 months | Still abnormal with new growth affected → repeat mycology before any further course. |
| Tinea capitis cure | Clinical review ± repeat mycology | End of treatment | Still positive → extend or switch drug; dermatology if not cured. |
| Glycaemia | HbA1c | Now; then per NICE NG28 if diabetic | ≥48 mmol/mol → diabetes (single result if symptomatic); 42–47 → non-diabetic hyperglycaemia, lifestyle support and at least annual recheck (NICE PH38). |
| Diabetic foot | Foot risk assessment | At diagnosis; at least annually (NICE NG19) | Ulcer or infection → foot protection / MDT service; same day if spreading infection or ischaemia. |
⚠ Three scenario-specific phrases — use these verbatim
What to document
- Oral antifungal without confirmation/safety checks
- Treating the rash but ignoring diabetes/source/hygiene
- Continuing steroid monotherapy
Who you are
Gary Pollard, 56. Several thickened, yellow, crumbly toenails for over a year — you find them embarrassing and want "the tablets" to clear them. You also have an itchy, scaly, peeling rash between your toes and on the sole, and a faint scaly ring in your groin. You used a steroid cream from the pharmacy on the groin, which soothed it at first but then it spread and lost its ring shape. Lately you've put on weight, feel thirsty and tired, and your dad had diabetes. You're hoping to walk out with a prescription for antifungal tablets.
Hidden concerns (reveal if explored)
Embarrassment (main): the nails bother you cosmetically; you want them sorted.
Downplayed symptoms: you'll mention the thirst, tiredness and weight gain only if asked — you hadn't connected them to anything.
Impatience: you just want the tablets and may be mildly resistant to "more tests".
Clinical details if asked
- Onychomycosis (several toenails, >1 year); tinea pedis (itchy, scaly, peeling between toes/sole); tinea cruris (groin ring)
- Used a topical steroid on the groin → spread and became atypical
- Recent weight gain, thirst, polyuria, fatigue; father had type 2 diabetes
- No hot/red/swollen leg (no current cellulitis); no changing/ulcerating lesions
- On no regular medication; happy to have a nail clipping and blood tests
Reactions at key moments
- If the doctor just prescribes oral antifungals: you're pleased — so a strong candidate must confirm first and explain why.
- On "let's confirm with a nail clipping": mildly impatient, accepting when the reasons (long course, liver) are explained.
- On the diabetes check: surprised but take it seriously given your dad.
- On the steroid having made it worse: "Oh — I thought it was helping."
- Challenge line: "Can't you just give me the tablets now and skip all the tests?"
Resolution: Gary is well served if the GP: (1) recognises the multi-site dermatophyte infection (tinea pedis/cruris/onychomycosis) and the steroid-modified groin lesion; (2) confirms the nails (clippings, microscopy & culture) with baseline LFTs/interaction check before committing to oral terbinafine, explaining why; (3) searches for the underlying cause and checks HbA1c given his thirst/weight/fatigue/family history (likely undiagnosed diabetes); (4) treats the skin topically, stops the steroid, treats the feet as the source, and gives hygiene/recurrence advice; (5) safety-nets and arranges follow-up. He is poorly served if simply handed oral antifungals without confirmation or any search for the cause.
Tinea: annular, scaly advancing edge, central clearing — corporis/cruris/pedis/capitis/unguium. Candida: moist folds/mucosa, satellite pustules. Pityriasis versicolor: pigmented scaly macules. Steroid-modified tinea: atypical/spreading on steroid → stop steroid, scrape, treat as fungal. Confirm nails/scalp (microscopy & culture) before oral antifungals.
Topical first for skin tinea/candida; oral (terbinafine/itraconazole, confirmed, LFTs/interactions) for nails; tinea capitis = oral + treat contacts (kerion promptly). Treat the source (feet) & hygiene; athlete's foot is a cellulitis portal. Find the cause: recurrent/widespread → HbA1c (diabetes), consider immunosuppression/HIV. Don't label a changing/ulcerating lesion "fungal" — consider skin cancer.