Zox

Quick links to important sections

Zox

Method of action: Antiparasitic

Treatment option: Diarrhea

Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Zox

Property Description
Active Ingredient Nitazoxanide (NTZ)
Form Tablet; Oral Suspension
Pharmacological Class Antiprotozoal Agent; Thiazolide
Common Use Treating certain intestinal infections
Origin Synthetic derivative

The medicine known by the active ingredient Nitazoxanide (NTZ) is a broad-spectrum anti-infective agent, classified within the unique thiazolides drug class. Nitazoxanide is a synthetic nitrothiazolyl-salicylamide derivative and is typically obtained by prescription.

This single-ingredient product is defined by its core action: to address certain intestinal infections. The drug is designed to be administered orally, whereupon it is rapidly converted into its principal active form, tizoxanide (desacetyl-nitazoxanide). This unique metabolic activation is a differentiating factor, as it means the body utilizes a powerful metabolite to deliver its therapeutic effect.

The primary function of Nitazoxanide is as an antiprotozoal agent, and its broad-spectrum capability is recognized for its role in controlling susceptible microorganisms that cause illness, such as those that lead to diarrhea. This is often used when a general anti-infective approach is required for parasitic intestinal conditions. Nitazoxanide is available in two main dosage form(s): a compressed tablet and an oral suspension (powder for reconstitution). The availability of the oral suspension makes it particularly suitable for the pediatric patients target audience, which is a key differentiating aspect of its formulation.

Regulatory References

  1. MedlinePlus Drug Information

What side effects are possible with Zox?

Possible Side Effects and Safety Information for Zox

Adverse Reactions

The safety profile of Zox is based on reports from clinical trials and post-marketing surveillance, detailing adverse events across various body systems. It is important to note that the occurrence and severity of side effects can vary.

Commonly Reported Adverse Reactions:

Reactions frequently observed in clinical data include headache, nausea, abdominal pain, vomiting, and diarrhea. Other common effects include dizziness and discolored urine (Chromaturia).

Serious and Clinically Significant Adverse Reactions:

Serious concerns highlighted in official documentation include the potential for severe allergic reactions (hypersensitivity) and effects on organ systems. Caution is specifically advised regarding use in patients with hepatic or renal disease, as the medication is metabolized by the liver and excreted by the kidneys, and dose adjustments or avoidance may be necessary.

Safety Considerations and Restrictions

Population-Specific Warnings:

Safety is not established in all populations. Zox is typically contraindicated in individuals with known hypersensitivity to the drug's components. Caution is advised for its use during pregnancy and lactation; the drug may pass into breast milk, and its use during pregnancy should only occur if clearly necessary. It should be administered with caution to patients with hepatic or biliary disease and renal disease.

General Safety Notes:

Due to the potential for dizziness and drowsiness, patients must be advised not to drive or operate machinery until they understand how the drug affects them. The medication is highly bound to plasma protein; therefore, caution is necessary when co-administering it with other highly plasma protein-bound drugs that have a narrow therapeutic index.

Overdose and Emergency Response

Overdose and when to seek help

The official regulatory documentation states that limited information is available regarding specific clinical manifestations of nitazoxanide overdosage in humans. In the event of a suspected overdose, official guidance mandates that you contact a poison control center or emergency room at once.

Immediate emergency services must be contacted if the individual exhibits severe signs. This includes if the person has collapsed, had a seizure, has trouble breathing, or cannot be awakened.

Management of a nitazoxanide overdose is based on supportive care. Regulatory information confirms there is no specific antidote known for this substance. Patients are to be observed and given symptomatic and supportive treatment. Furthermore, gastric lavage may be appropriate soon after the oral administration of the substance. The effectiveness of dialysis for the removal of nitazoxanide from the circulation is unknown.

Therapeutic Uses of Zox

What Zox Treats: Main Uses and Benefits

Targeted Treatment for Confirmed Parasitic Infections

This medication is an antiprotozoal agent used in situations involving certain distressing symptoms. Applied across domains where additional symptomatic support is needed, the medicine is commonly used to help with diarrhea in situations where patients experience infections from the protozoan parasites, specifically Giardia lamblia and Cryptosporidium parvum. It is relevant for easing conditions characterized by periods of heightened symptoms that are generally confirmed to be parasitic in origin.


Relief from Acute and Persistent Diarrhea

The medicine may assist with managing symptoms related to physical discomfort, which is commonly used to help with addressing acute or persistent diarrhea (watery or loose stools) and accompanying abdominal cramping and general distress. Quick Fact: Symptom Management Focus

Applied across domains where additional symptomatic support is needed, this medicine contributes to easing the overall symptom load and helps maintain a sense of stability when symptoms are more noticeable. It may be part of symptomatic management in situations where functional stability becomes affected. This therapeutic approach is generally considered relevant for easing symptoms in immunocompetent adults, adolescents, and pediatric patients (one year and older). The availability of the oral suspension formulation is considered relevant for easing symptoms in pediatric patients.

“This antiprotozoal support is applied in clinical settings that involve acute or unstable symptom patterns linked to specific parasitic causes.”

Regulatory References

  1. NIH DailyMed Drug Information

Eligibility and Restrictions for Use

Who Can and Cannot Use Zox?

The eligibility for using Zox (Nitazoxanide) is defined by strict regulatory criteria concerning a patient's age, immune status, and prior medical history.


Absolute Non-Eligibility (Contraindication)

The medicine is strictly contraindicated for any patient with a known history of hypersensitivity or allergic reaction to nitazoxanide or any of the inactive ingredients in the formulation.


Age-Group Eligibility

Eligibility is determined by the dosage form. The oral suspension is approved for pediatric patients 1 year to 11 years of age. The tablets are approved for patients 12 years of age and older (adolescents and adults). Use of the oral suspension is not established in infants less than one year old. Furthermore, the tablets should not be administered to children 11 years or younger.


Conditional Use and Restrictions

Regulatory labeling includes specific limitations of use for certain populations. Efficacy has not been shown for treating Cryptosporidium parvum infection in HIV-infected or immunodeficient patients. Caution is recommended when prescribing to individuals with compromised hepatic (liver) or renal (kidney) function, as safety data in these groups are limited. For pregnant or nursing women, use is generally advised only if the potential benefit outweighs the potential risk.

What should I know about interactions with other medicines?

Interactions with Medicinal Products

The interaction profile of Nitazoxanide is characterized by its high affinity for plasma proteins. The active metabolite, tizoxanide, is extensively bound to plasma proteins, exceeding 99.9% binding. This high level of binding establishes a potential for a pharmacokinetic interaction when the product is co-administered with other highly plasma protein-bound medicinal products that have narrow therapeutic indices. This documented interaction pattern may involve competition for binding sites, which can subsequently lead to an increase in the plasma concentration of the co-administered medicine. Regulatory documentation cites Warfarin as an example of a drug where this binding site competition may be relevant.

Nitazoxanide is not anticipated to have significant interactions with medicinal products that are metabolized by or inhibit Cytochrome P450 (CYP) enzymes. This is because the active metabolite is eliminated primarily through glucuronidation, rather than the CYP enzyme system. No medicinal products are formally classified as contraindicated combinations based solely on a drug-drug interaction risk. Furthermore, no mandatory timing separation rules are documented in the official regulatory information.

Interactions with Food

Co-administration with food significantly alters the drug’s exposure and enhances oral bioavailability. Taking the tablet formulation with food leads to an approximate two-fold increase in the Area Under the Curve (AUC) and an approximately 50% increase in the Peak Plasma Concentration (Cmax) of the active metabolite, tizoxanide.

Mechanism of Action

How Zox Works

The mechanism of Zox (Nitazoxanide) is defined by its active metabolite, tizoxanide, which exerts action across two primary domains against susceptible pathogens. The first domain involves metabolic disruption against protozoa and anaerobic bacteria. Tizoxanide acts as a noncompetitive inhibitor of the enzyme pyruvate:ferredoxin/flavodoxin oxidoreductase (PFOR). This enzyme is essential for the pathogen's anaerobic energy metabolism. Inhibition of PFOR interrupts the electron transfer required for ATP synthesis, leading to rapid energy depletion and a cytocidal effect on the organisms.

The second domain addresses susceptible intestinal helminths. Here, tizoxanide interacts with and activates specific glutamate-gated chloride ion channels in the worm's neuromuscular tissue. This causes a massive influx of chloride ions and subsequent hyperpolarization of the cells. This physiological consequence induces flaccid paralysis of the worm, allowing the organism to be expelled by peristalsis.

Secondary to these antipathogen actions, the active metabolite influences host pathways (e.g., NQO1, AMPK). This is associated with the modulation of pro-inflammatory mediator expression, such as IL-6 and TNF-alpha.

Dosage and Administration Information

How Zox (Nitazoxanide) Is Used

Nitazoxanide, commonly referred to as Zox, is administered according to a strict, standardized regimen focusing solely on the procedural aspects of intake. The medicine is only for oral use and is prescribed as a short-term course with a fixed duration of 3 days.


Dosing and Frequency

The required dose must be taken twice daily (every 12 hours). A critical instruction for proper use is the requirement that each dose must be consumed with food to ensure enhanced absorption of the active metabolite, tizoxanide.

Age Group Dosage per Administration Formulation Frequency and Duration
Adults and Adolescents (12+ years) 500 mg Tablet or Suspension Twice Daily for 3 Days
Pediatric Patients (4–11 years) 200 mg Oral Suspension Twice Daily for 3 Days
Pediatric Patients (1–3 years) 100 mg Oral Suspension Twice Daily for 3 Days

Administration Requirements

The two available formulations—the 500 mg tablet and the 100 mg/5 mL oral suspension—are not interchangeable due to differences in their bioavailability. The tablet is not approved for children 11 years of age or younger. If using the oral suspension, the powder requires reconstitution with a specific amount of water and must be shaken well immediately before each dose is measured and taken. If a dose is missed, it should be taken as soon as remembered on the same day, unless it is already time for the next scheduled dose, in which case the missed dose should be skipped.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Zox

Evidence for use in Giardia lamblia Infection

The compound Nitazoxanide was studied for short-term Randomized Controlled Trials (RCTs). These studies monitored outcomes related to physical discomfort and systemic or functional imbalance, primarily focusing on conditions associated with acute or disruptive episodes of diarrhea caused by the Giardia lamblia parasite. The research involved patients diagnosed with giardiasis, including immunocompetent children (ages 1–11 years) and adults and adolescents (12 years and older). Researchers examined both the patient's clinical response status (how their diarrhea symptoms changed) and the parasitological response (whether the parasite was found in post-treatment stool samples).

Regulatory submissions describe patterns observed in studies involving both children and adults. Comparative trials examined patterns of parasite clearance in patients relative to those documented for the established comparator drugs. However, some trial reports indicated an inconsistency between the documented clinical response status and the related microbiological clearance rates in certain groups of patients.

Evidence for use in Cryptosporidium parvum Infection

The product was studied for its use in contexts involving the Cryptosporidium parvum parasite. This evaluation was primarily done through double-blind, placebo-controlled RCTs used in research exploring short-term symptom changes. Key endpoints research examined included outcomes related to physical discomfort and the status of parasite oocysts in post-treatment stool. This research was largely focused on immunocompetent children and non-immunodeficient adults presenting with conditions characterized by fluctuating or episodic manifestations of diarrhea.

Trial analysis submitted for regulatory review reported measurements of both clinical response status and oocyst eradication in treated immunocompetent patients. However, regulatory documents note findings from trials which did not establish differences from placebo in patients who were HIV-infected or immunodeficient. This distinction highlights a key factor in the evidence landscape for this indication.

Synthesis of Research Gaps and Uncertainty

The research landscape highlights what is known — and what is still uncertain. Follow-up durations were limited across the research base, leading to the uncertainty that long-term effects are not fully established regarding durability of response. A notable gap is the explicit lack of evidence for this population in immunodeficient patients for Cryptosporidium infection, meaning findings apply only to the populations studied (immunocompetent). Data for certain groups remain insufficient, particularly older adults, and there is limited information on the use of the product in patients with significant chronic comorbidities.

Frequently Asked Questions (FAQ)

Common questions about Zox (FAQ)

Q: Are there any food or drinks I should avoid while using Zox?

Regulatory documents mention that Zox is taken with food to ensure the medicine is properly absorbed by the body. However, no specific food or drinks, such as grapefruit or alcohol, are explicitly listed as forbidden or contraindicating in official documents.


Q: Does Zox require a special diet?

The regulatory instruction is that the medicine is consumed with food to increase its exposure in the body. However, regulatory labeling does not indicate that any special diet is required or recommended beyond this general requirement.


Q: What happens when a person stops taking Zox?

Zox is defined as a fixed, short-term course of treatment, typically lasting 3 days. No specific instructions regarding withdrawal, tapering, or gradually stopping the medication are noted in the official labeling upon completion of the course.


Q: Why does the official document mention 'Drug Class X' for Zox?

Zox is officially classified as an Antiprotozoal agent and a Thiazolide. This classification is based on its core chemical structure and its established action to disrupt the energy metabolism of susceptible organisms. Official documents use this classification to categorize the medicine for regulatory and professional use.


Q: How is Zox cleared from the body?

Zox is rapidly converted into its active form, tizoxanide, which is eliminated by the body primarily through a process called glucuronidation. Regulatory pharmacokinetic data states that the active form and its breakdown products are then naturally excreted in both the urine and the feces.


Q: How long after stopping Zox do the effects wear off?

Regulatory pharmacokinetic information indicates that the half-life of the active metabolite (tizoxanide) is approximately 7.3 hours. The half-life is the time it takes for half of the drug to be eliminated from the body.


Q: Why is Zox sometimes referred to by its chemical name?

The chemical name, Nitazoxanide, is the official name of the active ingredient. It is often used by healthcare professionals and in formal documents to clearly distinguish the product from its various brand names.


Q: Does Zox have a risk of dependency or addiction?

Official drug status classifications indicate that Zox is not scheduled as a controlled medication by the Drug Enforcement Administration (DEA). This means the medication is not associated with a known risk of dependency or addiction.


Q: Is it normal to feel tired after starting Zox?

Official adverse reaction listings report that some patients experience dizziness and somnolence (drowsiness). These effects may indirectly contribute to a feeling of tiredness, but other reactions such as fatigue or a general lack of energy are sometimes reported less commonly.


Q: What are the signs of an allergic reaction to Zox?

Official safety information indicates that Zox is strictly contraindicated (not to be used) in anyone with known hypersensitivity to the drug's components. Severe allergic reactions may include sudden symptoms such as skin rash, hives, or swelling of the face, lips, tongue, or throat.


Q: Are there any known long-term side effects that are rare but serious?

Regulatory research summaries state that long-term effects are not fully established due to limited follow-up periods in the initial clinical trials reviewed. Official safety information does list serious adverse reactions, but their long-term prevalence is uncertain.


Q: Can Zox cause weight changes?

Official clinical trial data and adverse reaction reports do not list weight changes (either weight gain or weight loss) among the commonly or less commonly reported effects associated with Zox.


Q: Does Zox cause sensitivity to the sun?

Photosensitivity or increased sun sensitivity is not listed among the common or less common adverse reactions in regulatory labeling.


Q: Does Zox affect sleep patterns?

Regulatory sources list dizziness and somnolence (drowsiness) as reported side effects, which may affect wakefulness. In less than 1% of patients, insomnia (difficulty sleeping) has also been reported in some studies.


Q: Can Zox be taken with common over-the-counter pain relievers?

Regulatory documents state that Zox's active metabolite is highly protein-bound and may compete for binding sites with other highly plasma protein-bound medicines that have narrow therapeutic indices (e.g., Warfarin). There is no specific caution regarding common over-the-counter pain relievers.


Q: Do any common blood pressure medicines interact with Zox?

Regulatory documents cite a potential interaction risk with other highly plasma protein-bound medicines that have a narrow therapeutic index. Specific blood pressure medicines are not mentioned, but the potential risk relates to the binding profile, not the class of co-administered medicine.


Q: What kind of monitoring might be required while taking Zox?

Routine laboratory monitoring is not specified for all patients during the short course of treatment. Monitoring is typically only suggested when Zox is co-administered with other highly protein-bound medicines that have a narrow therapeutic index.


Q: Is Zox safe for older adults to use?

Studies reviewed for regulatory approval included adult populations (12+ years). However, the official documentation notes that safety data on the use of Zox in older adults and patients with significant chronic health conditions are limited.


Q: Is Zox known to interact with herbal supplements?

No specific interactions with herbal supplements are formally listed in official regulatory labeling.


Q: Can Zox interfere with laboratory test results?

Clinical data reviewed for regulatory approval sometimes report slight, non-significant changes in specific laboratory values, such as liver enzymes. However, no significant, systematic interference with general laboratory tests has been noted in studies using the approved dose.


Q: Is there a generic version of Zox available?

Yes, a generic version containing the active ingredient Nitazoxanide is available. This version is considered therapeutically equivalent to the brand-name product.


Q: Can I drink alcohol while taking Zox?

No specific interaction between Zox and alcohol is formally listed in regulatory documents.


Q: Does Zox have any known interaction with grapefruit?

No specific interaction between Zox and grapefruit or grapefruit juice is noted in regulatory labeling.

How should Zox be stored and disposed of?

How to Store and Dispose of Zox (Nitazoxanide)

The official storage and disposal instructions for Nitazoxanide are designed to maintain product integrity and ensure public safety.

Storage Requirements

Condition Requirement
Temperature Store at controlled room temperature (20 C to 25 C).
Environment Keep away from excess heat and moisture; do not store in the bathroom.
Packaging Keep the medicine in its original container with the cap tightly closed.
Child Safety Store out of sight and out of reach of children.

Stability and Disposal

The reconstituted oral suspension must be discarded after 7 days of mixing, even if stored correctly.

For disposal, the preferred method is a community drug take-back program. If a program is unavailable, the product should be mixed with an undesirable substance, such as dirt or used coffee grounds, placed in a sealed bag, and discarded in the household trash. Nitazoxanide is not on the list of medicines recommended for flushing down the toilet.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

Available in countries:

Equivalent of Zox found in:

A-Z Index: