Antiparasitic / Antiviral — Cryptosporidiosis / Giardia / Clostridium difficile Pregnancy: Use with caution — limited human data; avoid if possible

Nitazoxanide

Brand names: Alinia, Cryptaz

Adult dose

Dose: Giardiasis / Cryptosporidiosis: 500 mg twice daily × 3 days; C. difficile (adjunct, off-label UK): 500 mg twice daily × 10 days

Route: Oral (tablets or suspension)

Frequency: Twice daily

Max: 1 g/day

Not licensed in UK (EMA not approved) — available via specialist import. Licensed in USA. Used for Cryptosporidium parvum in immunocompetent patients (self-limiting in immunocompetent; severe and persistent in immunocompromised — HIV/transplant). Primary treatment for cryptosporidiosis in HIV remains ART to restore immunity. Also active against rotavirus, norovirus, hepatitis B and C (investigational).

Paediatric dose

Route:

Children 1–3 years: 100 mg BD × 3 days; 4–11 years: 200 mg BD × 3 days; ≥12 years: adult dose; oral suspension (100 mg/5 mL) available in USA

Dose adjustments

Renal

Use with caution in severe renal impairment — limited data

Hepatic

Use with caution in hepatic impairment

Clinical pearls

Cryptosporidiosis in HIV: nitazoxanide reduces diarrhoea duration in immunocompetent patients; in HIV, ART (restoring CD4 >100 cells/mm³) is the most effective intervention — nitazoxanide has limited benefit in severe immunosuppression
Yellow urine: a harmless side effect of the metabolite excreted in urine — reassure patients to prevent unnecessary concern or discontinuation
Giardiasis alternatives: metronidazole 400 mg TDS × 5 days (first-line in UK, though resistance emerging) or tinidazole single 2 g dose — nitazoxanide is an alternative in resistant cases or metronidazole intolerance
Unlicensed in UK: obtain through specialist import (imported medicines service — NHS England); document clinical justification

Contraindications

Hypersensitivity to nitazoxanide

Side effects

GI disturbance (nausea, diarrhoea, abdominal pain)
Headache
Yellow-green discolouration of urine and eyes (metabolite tizoxanide glucuronide — harmless, inform patient)
Elevated LFTs

Interactions

Highly protein bound — theoretical interactions with other protein-bound drugs
Warfarin — monitor INR

Monitoring

Stool microscopy and culture (eradication)
FBC and LFTs
HIV viral load and CD4 (if HIV co-infected — primary treatment priority)
Hydration and electrolytes

Reference: BNFc; BNF 90; IDSA Cryptosporidiosis Guidelines; FDA Nitazoxanide Prescribing Information; PHE Cryptosporidium Guidelines; Rossignol Meta-Analysis. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways