Itraconazole for fungal skin disease

Oral itraconazole earns a Gold Coast script less often than oral terbinafine — and never as a reflex after one tube of cream. It is a useful second antifungal when the organism is a yeast, when terbinafine has failed or cannot be used, or when pityriasis versicolor is too extensive for topical treatment. It is also a high-interaction, negative-inotrope drug. The heart-failure contraindication and the CYP3A4 list catch people out more often than the fungus does.

Do not swap brands

Lozanoc 50 mg is not the same as 50 mg of conventional itraconazole. One Lozanoc 50 mg capsule is treated as therapeutically equivalent to one 100 mg conventional capsule, but the products are not bioequivalent and are not interchangeable (Lozanoc CMI boxed warning, January 2024). Write the brand. Sporanox capsules were discontinued in Australia from 28 February 2023; current conventional 100 mg brands include Itranox, Itracap and APO-Itraconazole.

When it earns a script

Confirm the diagnosis before a long oral course. Send skin scrapings, nail clippings or plucked hair for microscopy and culture (PCR if the lab offers it). Abnormal nails are not always fungus — the Australasian College of Dermatologists notes that onychomycosis accounts for about half of dystrophic nails.

Topical first

Most localised tinea corporis, tinea cruris and interdigital tinea pedis respond to topical terbinafine 1% cream once or twice daily for one to two weeks (RACGP AJGP 2019). Limited pityriasis versicolor is also a topical job (ketoconazole or selenium sulphide). Oral itraconazole is indicated for dermatomycoses and pityriasis versicolor only if external treatment is not effective or not appropriate (Lozanoc ARTG indication; Itracap PI).

When oral therapy is reasonable

Failed or extensive tinea of body, groin, palms or soles after an adequate topical course — or disease too widespread to treat topically.
Tinea capitis — always oral. Topical drugs do not reach the follicle. In Australian GP practice oral terbinafine is preferred for Trichophyton; griseofulvin is often preferred for Microsporum. Itraconazole is an alternative. Paediatric use is not established in the PI and Lozanoc CMI says it is not recommended in children — treat as specialist or off-label unless you have a clear local protocol.
Onychomycosis — oral terbinafine is first-line for dermatophyte nails (AJGP 2019; Cochrane review cited there). Itraconazole is second-line if terbinafine fails, is not tolerated, or the organism is a yeast rather than a dermatophyte. ACD: candida often presents as paronychia with nail-fold change.
Extensive pityriasis versicolor that has failed topical treatment — this is one of the few skin jobs where an azole beats terbinafine, because terbinafine has little activity against Malassezia.
Candida of nail or persistent cutaneous candidiasis where topical therapy is not enough. Terbinafine is a poor yeast drug.

Terbinafine vs itraconazole in one line

Dermatophyte (typical tinea and most fungal toenails) → terbinafine first. Yeast, Malassezia, or terbinafine not suitable → itraconazole. Do not start either for nails without mycology if you can help it.

What is not a GP start

Systemic aspergillosis, histoplasmosis and lymphocutaneous or cutaneous sporotrichosis sit on the PI and on the PBS list, but they are not community tinea. Refer. Itraconazole is not the drug for kerion, suspected deep mycosis, or an immunocompromised patient with spreading disease unless you are already in a shared-care arrangement.

Figure 1. Topical first for local tinea; oral terbinafine for most dermatophyte disease; oral itraconazole when the organism is a yeast, pityriasis versicolor is extensive, or terbinafine is not an option. Heart failure blocks itraconazole for skin and nails.

How to prescribe in Australia

The two capsule families

	Lozanoc (SUBA-itraconazole)	Conventional capsules
Strength	50 mg	100 mg (Itranox, Itracap, APO)
Equivalence	1 × 50 mg ≈ 1 × 100 mg conventional	Reference dose in most guidelines and the Itracap PI
Food	With or without food (Lozanoc CMI)	Immediately after a meal; swallow whole (Itracap PI)
Acid	CMI still lists PPIs, H2-blockers and antacids as interacting medicines — do not assume they are irrelevant	PPIs / H2-blockers / antacids reduce absorption. Antacids ≥2 hours after the capsule. Cola beverage if achlorhydria or on acid suppression (Itracap PI 4.4)
Children / elderly	Not recommended (CMI)	Use only if benefit outweighs risk (PI)

I was not able to open the full current Lozanoc Product Information PDF (the medsinfo PI endpoint returned 404). Doses below for Lozanoc come from the January 2024 CMI. Conventional doses come from the Itracap PI revised 7 January 2026. If the two documents ever diverge, follow the PI of the brand on the script.

Figure 2. Dose-matching: Lozanoc 50 mg maps to conventional 100 mg. Do not write a 50 mg conventional dose, and do not substitute brands mid-course.

Adult doses used in Australian GP practice

Numbers in the conventional column are on-PI (Itracap). Lozanoc numbers are the CMI “usual doses” and are half the milligram amount. Pulse nail therapy is on-PI for conventional capsules and is described in the Lozanoc CMI.

Indication	Conventional (Itracap PI)	Lozanoc 50 mg (CMI)
Tinea corporis / cruris (after topical failure)	100 mg daily for 2 weeks	1 capsule daily for 2 weeks
Tinea pedis / manus	100 mg daily for 4 weeks	1 capsule daily for 4 weeks
Pityriasis versicolor (failed other treatment)	200 mg once daily for 1 week	CMI “other skin infections”: 2 capsules daily for 1 week
Onychomycosis — continuous	200 mg once daily for 3 months	2 capsules once daily for 3 months
Onychomycosis — pulse	200 mg twice daily for 1 week, then 3 weeks off. Two pulses for fingernails; three for toenails	2 capsules twice daily for 1 week, then 3 weeks off. Repeat once for fingernails, twice more for toenails

AJGP 2019 lists the same conventional pulse and continuous nail regimens and notes similar efficacy. AJGP 2026 quotes itraconazole 100 mg daily for 2–4 weeks as an oral alternative to terbinafine for tinea — that matches the PI corporis/cruris and pedis/manus schedules, not a separate off-PI dose.

Skin marks keep improving for weeks after you stop, because the drug sits in keratin. Nail appearance lags 6–9 months (Lozanoc CMI). Do not extend a nail course just because the plate still looks ugly at week 12.

PBS — do not invent an authority for tinea

PBS itraconazole (Lozanoc 50 mg item 10732W; Itranox/Itracap 100 mg item 8196J) is Authority Required (Streamlined) only for systemic aspergillosis, systemic sporotrichosis, systemic histoplasmosis (including disseminated or chronic pulmonary histoplasmosis), oropharyngeal candidiasis and oesophageal candidiasis. Tinea and onychomycosis are private scripts. Oral terbinafine 250 mg (item 2804N) is Authority Required for the indication “onychomycosis” — check the current PBS clinical criteria before you claim it; the public item page I opened listed that indication without extra streamed wording.

Adverse effects and monitoring

Common effects are gastrointestinal (nausea, pain, diarrhoea, constipation, dyspepsia) and headache or dizziness. Reversible liver-enzyme rises are listed as common in the Itracap PI. Serious harms are uncommon but they change the consent conversation.

Harm	What to do in GP
Congestive heart failure (negative inotrope)	Contraindicated if there is ventricular dysfunction, CHF, or a history of CHF, except life-threatening infection (Itracap PI 4.3). Heart-failure reports were more common at 400 mg total daily dose. Stop if dyspnoea, sudden weight gain, oedema or new nocturnal waking appears. Calcium-channel blockers add to the negative inotrope effect.
Hepatotoxicity	Rare cholestatic jaundice and very rare hepatitis or fatal acute liver failure — some in the first week, some without prior liver disease (Itracap PI 4.4). Strongly discourage use if enzymes are already abnormal unless the infection is serious. Consider LFT monitoring in anyone on treatment; Lozanoc CMI flags blood tests if the course is longer than one month. Stop and test if anorexia, nausea, dark urine, pale stool or jaundice.
QT prolongation	The danger is mostly the combination: raised levels of dofetilide, quinidine, domperidone, methadone and similar drugs. Those combinations are contraindicated.
Hypokalaemia	Reported; monitor potassium during high-dose therapy (PI). The US label (DailyMed, July 2026) also describes pseudoaldosteronism with hypertension and low potassium — labelled here as FDA information, not a TGA boxed statement.
Peripheral neuropathy	Stop the drug if neuropathy may be attributable to itraconazole (PI 4.4).
Hearing loss	Transient or permanent. Several reports involved quinidine (contraindicated). Stop if hearing changes.
Visual disturbance	Blurred vision or diplopia — warn about driving (PI 4.7).
Severe rash	SJS, TEN, AGEP and AGEP-like pustular eruptions are very rare. Stop and treat as an emergency.

Heart failure is a hard stop for skin and nails

The Australian PI contraindicates itraconazole capsules in patients with evidence of ventricular dysfunction such as CHF or a history of CHF, except for life-threatening or other serious infections. A fungal toenail is not that exception. The US Sporanox label carries a boxed warning to the same effect (DailyMed, revised July 2026) — useful corroboration, not Australian law. Counsel for breathlessness, ankle swelling and sudden weight gain even in people without known heart disease.

Pregnancy and breastfeeding — TGA category B3

Itracap PI: pregnancy category B3. Contraindicated in pregnancy except life-threatening systemic mycosis. Highly effective contraception during treatment and for two months after the last dose, with a barrier method as well (PI 4.6). Lozanoc CMI is slightly looser in wording (“until the next menstrual period”) — follow the PI of the brand you prescribe; two months is the safer conventional-PI instruction.

Small amounts appear in breast milk (infant exposure estimated about 450-fold lower than the mother’s in one 400 mg/day calculation). Weigh benefit against risk; if in doubt, do not breastfeed (Itracap PI).

Interactions that matter in GP

Itraconazole is metabolised by CYP3A4 and is a potent CYP3A4 inhibitor. It also inhibits P-glycoprotein and BCRP (Itracap PI 4.5). Plasma levels can stay relevant for 7–14 days after stopping. The lists below are GP-useful examples from the Itracap PI (7 January 2026) and Lozanoc CMI (January 2024). They are not complete. Check the current PI and an interaction checker for the named product.

Figure 3. Stop or avoid the high-risk CYP3A4 substrates; monitor warfarin and some calcium-channel blockers; watch drugs that flatten itraconazole levels. Conventional capsules also need gastric acid.

Action	Examples that actually land in GP
Stop / do not co-prescribe	Simvastatin, lovastatin, lomitapide; oral midazolam, triazolam; apixaban, rivaroxaban, dabigatran, ticagrelor; eplerenone; ivabradine; felodipine, lercanidipine, nisoldipine; lurasidone; quinidine, dofetilide, dronedarone, disopyramide; domperidone; ergot alkaloids; colchicine in renal or hepatic impairment; venetoclax during initiation/ramp-up.
Avoid unless the benefit is clear; monitor	Warfarin (INR can rise); atorvastatin (lowest dose); diltiazem, verapamil and other dihydropyridines (additive negative inotrope plus raised CCB levels); digoxin; oxycodone and fentanyl; ciclosporin, tacrolimus, sirolimus, everolimus; inhaled budesonide or fluticasone; repaglinide, saxagliptin. Itracap lists quetiapine as contraindicated — treat that as a stop, not a monitor.
These flatten itraconazole	Rifampicin, rifabutin, isoniazid; carbamazepine, phenytoin, phenobarbital; efavirenz, nevirapine. For conventional capsules: PPIs, H2-blockers and antacids reduce absorption. Do not start a nail course on rifampicin and expect it to work.

Wait at least two weeks after the last itraconazole capsule before restarting a contraindicated CYP3A4 substrate (Lozanoc CMI).

In clinic: a five-line checklist

Is oral therapy actually indicated? Local tinea → topical. Dermatophyte nail or most oral tinea → terbinafine first. Itraconazole for yeast, extensive pityriasis versicolor, or terbinafine failure/intolerance.
Heart, liver, pregnancy. No CHF or prior CHF for skin/nails. Baseline LFTs if the course will run beyond a few weeks or there is any liver history. Not in pregnancy; contraception for two months after (conventional PI).
Medicines list, including the PPI. Statin, DOAC, warfarin, midazolam, colchicine, CCB, eplerenone, lurasidone, rifampicin, carbamazepine. If they are on a PPI and you choose conventional capsules, absorption may fail — take after food, separate antacids, consider cola, or use Lozanoc and still check the PI.
Write the brand and the milligram dose that belongs to that brand. Lozanoc 50 mg is a different object from Itranox 100 mg. Skin/nail courses are private; do not put a tinea authority on a PBS itraconazole item.
Counsel the stop signs. Breathlessness, swelling, sudden weight gain; dark urine or jaundice; tingling in the feet; hearing or vision change; rash with blistering. Skin looks better after you stop; nails take months. Review if there is no mycological logic for a second course.

Gold Coast takeaway

I use topical terbinafine for ordinary tinea, oral terbinafine for proven dermatophyte nails, and I reach for itraconazole when the lab says candida or Malassezia, or when terbinafine is not an option. I do not write it if there is heart failure, a simvastatin or a DOAC I cannot pause, or a woman who may conceive in the next two months. I write the brand so the pharmacy does not “generic substitute” Lozanoc for Itranox.

Therapeutic Guidelines (eTG) and the Australian Medicines Handbook were not opened — both are paywalled from this environment. If your practice eTG differs on first-line oral tinea, follow eTG and treat this note as a PI-and-AJGP reading.