Antiparasitic / Antiviral — Cryptosporidiosis / Giardia / Clostridium difficile Pregnancy: US label §8.1: there are no data with nitazoxanide in pregnant women to inform a drug-associated risk. No teratogenicity or fetotoxicity was observed in animal reproduction studies in pregnant rats and rabbits dosed during organogenesis at exposures 30 times and 2 times, respectively, the exposure at the maximum recommended human dose of 500 mg twice daily on a body-surface-area basis. In the US general population the estimated background risk of major birth defects and miscarriage in clinically recognised pregnancies is 2-4% and 15-20% respectively.

Nitazoxanide

Brand names: Alinia, Cryptaz

Nitazoxanide is an antiprotozoal and antihelminthic agent used for infections such as cryptosporidiosis and giardiasis caused by Cryptosporidium and Giardia.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: One 500 mg tablet every 12 hours for 3 days

Route: Oral - taken with food

Frequency: Every 12 hours

US label §2.1 (nitazoxanide tablets 500 mg, Camber Pharmaceuticals; no UK SPC was captured in this bundle - clinician to verify against UK prescribing references, noting nitazoxanide may not hold a UK marketing authorisation). INDICATION as stated in the label: treatment of diarrhoea caused by Giardia lamblia or Cryptosporidium parvum. The dosing table gives a single regimen - age 12 years and older, one 500 mg tablet taken orally every 12 hours with food, for 3 days. PAEDIATRIC (§2.1, §8.4): nitazoxanide TABLETS should NOT be administered to paediatric patients 11 years of age or younger, because a single tablet contains a greater amount of nitazoxanide than the recommended dosing in that age group (an oral suspension formulation exists but its dosing was not captured in this bundle). Safety and efficacy of the tablets in patients 12 to 17 years of age is established on three randomised controlled studies with 47 paediatric subjects; no per-kg dose is stated for the tablet, so no structured paediatric dose is recorded here. Verify any paediatric use against a children's formulary. ELDERLY (§8.5): clinical studies did not include sufficient numbers of subjects aged 65 and over; the greater frequency of decreased hepatic, renal or cardiac function and of concomitant disease or other drug therapy should be considered when prescribing. No renal or hepatic dose adjustment is stated in the captured label.

Dose auto-extracted from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity - contraindicated in patients with a prior hypersensitivity to nitazoxanide or any other ingredient in the formulations (US label §4.1)

Side effects

Abdominal pain (most common, in 2% or more of patients) (US label §6.1)
Headache (2% or more)
Chromaturia - discoloured urine (2% or more)
Nausea (2% or more)
Safety was evaluated in 2,177 HIV-uninfected subjects aged 12 months and older who received nitazoxanide tablets or oral suspension at the recommended dose for at least three days; no differences were reported between the adverse reactions in adults/adolescents and those aged 1 to 11 years

Interactions

Highly plasma protein-bound drugs with narrow therapeutic indices (e.g. warfarin) - tizoxanide, the active metabolite of nitazoxanide, is more than 99.9% bound to plasma protein, so competition for binding sites may occur; monitor for adverse reactions when co-administering (US label §7.1)

Clinical monograph

How it works

It interferes with the pyruvate:ferredoxin oxidoreductase enzyme-dependent electron-transfer reaction essential to anaerobic energy metabolism in susceptible organisms.

Prescribing in practice

Efficacy in cryptosporidiosis is reduced in immunocompromised patients, in whom restoring immune function is an important part of management.
It is taken with food, which increases absorption of the active metabolite.
It may cause a harmless yellow discolouration of the eyes or urine that should not be mistaken for jaundice.

Monitoring

Routine laboratory monitoring is not generally required; assess clinical response and resolution of symptoms.

Counselling the patient

Take this medicine with food.
A temporary yellow tinge to the eyes or urine can occur and is not harmful.

Evidence & guidelines

Activity against Cryptosporidium and Giardia is supported by clinical trials and reflected in current prescribing references.

Reference: IDSA Cryptosporidiosis Guidelines; FDA Nitazoxanide Prescribing Information; PHE Cryptosporidium Guidelines; Rossignol Meta-Analysis; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways