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Itraconazole is a triazole antifungal taken by mouth for nail, skin and systemic fungal infection; it acts only on fungi and has no role in bacterial illness.
- Oral reach for nail, skin and systemic fungal infection
- Blocks ergosterol synthesis at fungal CYP51
- Selective for fungi, with no antibacterial role
- A triazole taken by mouth rather than painted on
- Reaches nails and deep sites a cream never will
- Itraconazole blocks fungal lanosterol 14-alpha-demethylase to halt ergosterol synthesis, and its main metabolite hydroxy-itraconazole is itself substantially antifungal [1].
- Capsule absorption is erratic; the cyclodextrin oral solution and IV forms exist because consistent plasma levels are critical for systemic mycoses, whereas superficial infections tolerate variability because drug accumulates at the site [1].
- High affinity for mammalian CYP3A4 drives interactions with astemizole, terfenadine, rifampicin, oral contraceptives, H2 antagonists, warfarin and ciclosporin [3].
- Beyond antifungal use it is a potent Hedgehog antagonist acting at Smoothened by a mechanism distinct from cyclopamine, suppressing medulloblastoma growth in mice at ordinary antifungal serum levels [4].
- In a network meta-analysis of 26 RCTs and 8,136 patients, continuous itraconazole 200 mg had significantly greater odds of mycological cure in toenail onychomycosis than topical treatment, while pulsed regimens did not [6].
Mechanism
It blocks fungal lanosterol 14-alpha-demethylase (CYP51), starving the fungal membrane of ergosterol while toxic sterol precursors build up. Its affinity for host cytochrome P450 enzymes is the same property that makes its drug interaction list so long.
receptor fingerprint
Fungal lanosterol 14-alpha-demethylase (CYP51 / ERG11)Binds the haem iron of the fungal cytochrome P450 and blocks conversion of lanosterol to ergosterol, collapsing membrane integrity
Human CYP3A4Potent inhibitor as well as substrate, from high affinity for mammalian as well as fungal P450 enzymes
Smoothened (SMO) in the Hedgehog pathwayAntagonist by a mechanism distinct from cyclopamine and other known SMO antagonists; prevents ciliary accumulation of SMO after Hedgehog stimulation
Cardiac contractilityNegative inotropic effect shown in animal and clinical pharmacology studies
Safetyrisks and cautions, not medical advice
systemic azole with QT prolongation, negative inotropy and heavy CYP3A4 interaction potential; needs a confirmed fungal diagnosis and liver monitoring
Subjective profileweighing the evidence above
The whole value of this drug rests on the step most buyers skip, which is establishing that the problem is actually a fungus. A thick discoloured nail is fungal a good deal less often than people assume, and months of a systemic azole for the other cases buys nothing but raised liver enzymes and an interaction list long enough to matter. Negative inotropy makes it a poor choice in heart failure, and CYP3A4 inhibition quietly turns a lot of ordinary medicines into stronger versions of themselves while it is on board.
Where to buy
Suppliers
Vendors carrying Itraconazole, with live product details and codes. Links are affiliate links that support the wiki at no cost to you.
RUPharma🌐
Itraconazole
Research
- 1998first citedPharmacokinetics and pharmacology of terbinafine and itraconazole.
- 2019most recentMonotherapy for toenail onychomycosis: a systematic review and network meta-analysis.
- 1.Pharmacology of itraconazole.
- 2.Itraconazole.
- 3.Pharmacokinetics and pharmacology of terbinafine and itraconazole.
- 4.Itraconazole, a commonly used antifungal that inhibits Hedgehog pathway activity and cancer growth.
- 5.Congestive heart failure associated with itraconazole.
- 6.Monotherapy for toenail onychomycosis: a systematic review and network meta-analysis.
6 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
Notes and cautions
- Itraconazole carries a two-part US boxed warning: it must not be given for onychomycosis or dermatomycoses in patients with ventricular dysfunction such as congestive heart failure because of negative inotropic effects, with 58 CHF cases reported to the FDA [5]; and co-administration is contraindicated with a long list of CYP3A4 substrates including methadone, disopyramide, dofetilide, dronedarone, quinidine, ergot alkaloids, lurasidone, oral midazolam, pimozide, triazolam, felodipine, ranolazine, cisapride, lovastatin, simvastatin, ticagrelor and colchicine in renal or hepatic impairment, because of QT prolongation and other serious toxicity.
- Hepatotoxicity including fatal liver failure has been reported.
- Capsule absorption requires gastric acid, so proton pump inhibitors and H2 blockers substantially reduce exposure.