Chloroquine
Chloroquine is an antimalarial and antiprotozoal medicine used to treat and prevent certain types of malaria and to treat extraintestinal amebiasis (an amoeba infection that has spread beyond the gut).
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 6 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
📖 Chloroquine: Patient Information Guide
A plain-language walkthrough of Chloroquine — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Chloroquine Phosphate tablets are approved for the following uses:
- Treatment of uncomplicated malaria — caused by susceptible strains of Plasmodium falciparum, P. malariae, P. ovale, and P. vivax.
- Prevention (prophylaxis) of malaria — only in geographic areas where chloroquine resistance has not been reported.
- Extraintestinal amebiasis — infection with Entamoeba histolytica that has spread outside the intestines.
- Not for complicated malaria (such as cerebral malaria or malaria causing kidney failure).
- Not effective against the dormant liver-stage forms of P. vivax and P. ovale — an additional medicine (an 8-aminoquinoline) is needed to prevent relapses from those species.
⚙️How it works▾
Chloroquine is a 4-aminoquinoline — a type of antiprotozoal (anti-parasite) drug. It is thought to work by concentrating inside the malaria parasite's acid compartments and blocking the parasite's ability to neutralize a toxic byproduct of digesting hemoglobin, the oxygen-carrying protein in red blood cells. It may also interfere with parasite enzymes by interacting with DNA. The net result is that the parasite cannot survive inside red blood cells. It is also active against the trophozoite (feeding/active) stage of Entamoeba histolytica, which causes amebiasis.
Chloroquine only works against the blood-stage forms of the malaria parasite — not the gametocytes (the form that mosquitoes pick up) or the dormant liver-stage forms called hypnozoites in P. vivax and P. ovale. Resistance is widespread in P. falciparum worldwide and has been reported in P. vivax; parasites resistant to hydroxychloroquine also tend to be resistant to chloroquine.
💊How it's taken▾
Chloroquine Phosphate tablets are taken by mouth. The timing and number of doses depend on why you are taking it:
- Prevention: taken once a week, on exactly the same day each week — ideally starting two weeks before travel and continued for eight weeks after leaving the area.
- Treatment of malaria: doses are spread over three days, with the first (larger) dose followed by smaller doses at set intervals; children's doses are based on body weight.
- Extraintestinal amebiasis: taken daily over several weeks, usually combined with a separate medicine that targets the intestines.
Always follow your prescriber's exact directions. Do not stop early or adjust the dose on your own, and ask your pharmacist if you miss a dose.
🤒Side effects — in detail▾
Like any medicine, chloroquine can cause side effects. The most commonly reported ones include:
- Nausea, vomiting, stomach cramps, or diarrhea
- Loss of appetite
- Headache
- Blurred vision or difficulty focusing
- Itching or skin rash
- Dizziness
More serious reactions — including irreversible retinal (eye) damage, dangerous heart rhythm changes, severe low blood sugar, muscle weakness, liver injury, and neuropsychiatric effects such as depression or suicidal thoughts — require prompt medical attention. Contact your doctor or seek emergency care right away if any of these develop.
⚠️Warnings & precautions▾
- Eye/retinal damage: Irreversible damage to the retina (the light-sensing layer at the back of the eye) can occur, especially with long-term or high-dose use. A baseline eye exam is required within the first year of starting therapy, with follow-up exams as directed. Report any vision changes immediately.
- Heart risks: Chloroquine can cause life-threatening heart rhythm problems (including QT prolongation and torsades de pointes) and cardiomyopathy (heart muscle damage). Risk is higher at high doses, with certain other drugs, and in people with existing heart conditions or low potassium/magnesium. Fatal cases have been reported.
- Severe low blood sugar (hypoglycemia): Chloroquine can cause dangerously low blood sugar, even in people not taking diabetes medicines. Watch for sweating, shaking, confusion, or loss of consciousness.
- Neuropsychiatric effects: Depression, suicidal thoughts, hallucinations, and other mental health changes have been reported, typically within the first month. Contact your doctor right away if these occur.
- Muscle and nerve toxicity: Progressive weakness of the upper arms and legs and abnormal nerve function have been reported with long-term use. Periodic monitoring is needed.
- Chloroquine resistance: Resistance is widespread in P. falciparum and reported in P. vivax. Always confirm suitability for the region with your prescriber or the CDC before use.
- Danger to children: Accidental ingestion of even a small amount can be fatal in children. Store securely out of their reach at all times.
- Psoriasis and porphyria: Chloroquine can trigger severe psoriasis flares and can worsen porphyria; serious liver injury has been reported in people with porphyria cutanea tarda.
🔀What it interacts with▾
Chloroquine can interact with several medicines and supplements — tell your prescriber and pharmacist everything you take:
- Antacids and kaolin — reduce chloroquine absorption; take at least 4 hours apart.
- Cimetidine (a heartburn medicine) — slows chloroquine breakdown, raising blood levels; avoid combining.
- Insulin and diabetes medicines — chloroquine can amplify blood-sugar-lowering effects, raising the risk of hypoglycemia.
- Amiodarone and moxifloxacin — both can affect heart rhythm; combining with chloroquine increases the risk of dangerous arrhythmias.
- Ampicillin — chloroquine reduces how much of this antibiotic the body absorbs; separate doses by at least 2 hours.
- Cyclosporine — chloroquine can cause cyclosporine blood levels to rise sharply; close monitoring required.
- Mefloquine (another antimalarial) — increases seizure risk when combined with chloroquine.
- Tamoxifen — both drugs can damage the retina; this combination is not recommended.
- Praziquantel — chloroquine can reduce how much praziquantel the body absorbs.
- Rabies vaccine (intradermal human diploid-cell) — chloroquine at prophylactic doses can reduce the immune response to this vaccine.
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Known allergy to chloroquine or related 4-aminoquinoline medicines — do not take it.
- Existing retinal or visual field problems — chloroquine is contraindicated for uses other than acute malaria if such changes are already present.
- Heart disease, irregular heartbeat, or low potassium/magnesium — increased risk of serious heart problems; tell your prescriber.
- Psoriasis — chloroquine can trigger a severe flare; use only if benefits clearly outweigh risks.
- Porphyria — chloroquine can worsen this condition and cause serious liver injury; avoid if possible.
- Diabetes or blood-sugar-lowering medicines — chloroquine can cause severe low blood sugar; monitoring may be needed.
- Kidney problems — can affect chloroquine clearance and increase risk of retinal damage.
- Pregnancy — animal studies showed fetal harm at high doses; human data at recommended doses have not shown increased birth defects, but discuss the individual benefit-risk balance with your prescriber.
- Children — doses must be calculated by body weight and must never exceed adult doses; keep tablets completely out of reach, as even a small overdose can be fatal.
- Older adults — follow prescriber guidance, as the label notes special geriatric precautions.
🚑If you take too much▾
Chloroquine is absorbed very quickly, and a toxic amount can cause symptoms within minutes — including nausea, vomiting, headache, vision disturbances, seizures, dangerously low potassium, and severe heart rhythm problems that can lead to cardiac arrest. Even a relatively small amount can be fatal in young children. If you suspect an overdose, call emergency services immediately — this is a life-threatening emergency that requires urgent medical treatment including heart and breathing support.
📡Pharmacodynamics — effects in the body▾
Chloroquine acts against the blood-stage (erythrocytic) forms of susceptible Plasmodium species and against the active (trophozoite) stage of Entamoeba histolytica. It does not act against gametocytes or the dormant liver-stage (hypnozoite) forms of P. vivax and P. ovale. At the heart level, chloroquine can prolong the QT interval (a measure of heart electrical activity), which at higher doses raises the risk of serious arrhythmias. It has also been associated with phospholipidosis — an abnormal buildup of phospholipids in tissues — which underlies some of its toxicities in the heart, muscles, nerves, and kidneys.
🔬Pharmacokinetics — how your body processes it▾
Chloroquine is rapidly and almost completely absorbed from the gastrointestinal tract after oral dosing. About 55% of the drug in the bloodstream is bound to plasma proteins. It is widely distributed into body tissues — concentrating especially in the liver, spleen, kidney, and lungs — and is cleared from the body very slowly, meaning it stays in the system for a long time after the last dose. It is broken down (metabolized) in the body, with the main breakdown product being desethylchloroquine, and is primarily eliminated through the urine; urine acidification speeds up its excretion.
📦How to store it▾
Dispense in tight, light-resistant container as defined in the USP. Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° to 30°C (59° to 86°F)
📄 Written from Chloroquine’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
Supplements & herbs that interact with Chloroquine
29 supplements and herbal products have documented interactions with Chloroquine in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 2
- Moderate · 18
- Minor · 9
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Chloroquine — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is chloroquine used for? ▾
How do I take this tablet — is there a specific time of day or should I take it with food? ▾
What side effects should I watch out for, and which ones need a doctor's call? ▾
I've heard chloroquine can hurt your eyes. How worried should I be? ▾
Is it safe to take during pregnancy? ▾
Are there any common medicines I should avoid while taking chloroquine? ▾
Is Chloroquine available over the counter? ▾
When was Chloroquine first available? ▾
Who makes Chloroquine? ▾
💬 Answers drafted from Chloroquine’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Chloroquine comes
Chloroquine is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Tablet
How this form is used
- Chloroquine Phosphate tablets are used to treat uncomplicated malaria caused by susceptible strains of P. falciparum, P. malariae, P. ovale, and P. vivax.
- Chloroquine Phosphate tablets are used to prevent malaria in geographic areas where chloroquine resistance is not present.
- Chloroquine Phosphate tablets are used to treat extraintestinal amebiasis (amoeba infection that has spread beyond the gut).
- Chloroquine Phosphate tablets are taken by mouth — swallow with water and follow your prescriber's schedule exactly.
- For malaria prevention, Chloroquine Phosphate is taken once a week on the same day each week; continue for eight weeks after leaving the area.
- For malaria treatment, Chloroquine Phosphate doses are divided over three days as directed by your prescriber; children's doses are calculated by body weight.
- For extraintestinal amebiasis, Chloroquine Phosphate is taken daily over several weeks, often alongside another medicine targeting the intestines.
📊 Chloroquine across the U.S. market
How Chloroquine appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
Also listed with the FDA, not a patient dose form: Powder (3) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
📈 How widely Chloroquine is used
A general measure of how commonly Chloroquine is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Chloroquine is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Chloroquine prescribed? Of the 1,596 medications we measure, Chloroquine ranks #1,393 by Medicaid prescriptions — more than 13% of them.
Utilization by Chloroquine product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
chloroquine phosphate 250 MG Oral Tablet Most dispensed
Summed across the 2 of 9 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1117531
chloroquine phosphate 500 MG Oral Tablet
Summed across the 1 of 14 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1116758
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Chloroquine, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 3 of 23 listed Chloroquine NDCs with Medicaid activity.
🔍 Compare Chloroquine products
A representative set of FDA-listed product records for Chloroquine — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Tablet | ||||
| 250 mg | Oral | A-S Medication Solutions × 2 listings | ANDA | View NDC → |
| 250 mg | Oral | Amneal Pharmaceuticals of New York LLC × 3 listings | ANDA | View NDC → |
| 500 mg | Oral | Amneal Pharmaceuticals of New York LLC × 3 listings | ANDA | View NDC → |
| 500 mg | Oral | Avet Pharmaceuticals Inc. × 2 listings | ANDA | View NDC → |
| 500 mg | Oral | AvKARE × 2 listings | ANDA | View NDC → |
| 250 mg | Oral | Bayshore Pharmaceuticals LLC × 2 listings | ANDA | View NDC → |
| 500 mg | Oral | Chartwell RX, LLC × 2 listings | ANDA | View NDC → |
| 250 mg | Oral | Rising Pharmaceuticals, Inc. | ANDA | View NDC → |
| 500 mg | Oral | Rising Pharmaceuticals, Inc. | ANDA | View NDC → |
| 250 mg | Oral | Rising Pharma Holdings, Inc. × 2 listings | ANDA | View NDC → |
| 500 mg | Oral | Rising Pharma Holdings, Inc. × 2 listings | ANDA | View NDC → |
| 500 mg | Oral | Suven Pharmaceuticals Limited × 4 listings | ANDA | View NDC → |
| 💊Bulk drug substance | ||||
| 1 kg/kg | — | Cohance Lifesciences Limited | BULK INGREDIENT FOR HUMAN PRESCRIPTION COMPOUNDING | View NDC → |
| 1 kg/kg | — | Ipca Laboratories Limited | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Natco Pharma Limited | BULK INGREDIENT | View NDC → |
Showing 29 of 29 products — FDA National Drug Code Directory. See every product, package size and price: browse all 29 Chloroquine NDCs →
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Chloroquine — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Chloroquine in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Chloroquine went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 2393 2 dose forms · 5 strengths
-
Dose form (SCDF) Oral Solution RxCUI 756408No current FDA listingClinical drug / strength (SCD) phosphate 16 MG/MLRxCUI 1117346sulfate 13.6 MG/MLRxCUI 1117351 -
Dose form (SCDF) Oral Tablet RxCUI 371407In current FDA listingsClinical drug / strength (SCD) phosphate 250 MGRxCUI 1117531phosphate 500 MGRxCUI 1116758sulfate 200 MGRxCUI 1117353
Look up RxCUI 2393 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
📦 Supply & shortage status
Whether Chloroquine is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
Chloroquine belongs to the Antimalarial class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 6 FDA-filed SPL label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Avet Pharmaceuticals Inc. is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.