Prescription medication · Antimalarial
chloroquine
Also sold as Aralen. This medicine can treat uncomplicated malaria caused by certain types of parasites.
Data updated 2026-05-15
- 401
- FDA reports
- 5
- InteractionsFew interactions
- $2.12
- Generic price (NADAC)
What the data shows
chloroquine (Aralen) is a prescription Antimalarial, with 401 FDA adverse-event reports on file, with 5 documented drug interactions.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
chloroquine (Aralen) is a prescription Antimalarial. This medicine can treat uncomplicated malaria caused by certain types of parasites.
Chloroquine phosphate is a drug used to treat and prevent malaria. It can also treat a type of infection called extraintestinal amebiasis.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$2.12/unit
Generic Available
Yes (5 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine can treat uncomplicated malaria caused by certain types of parasites.
Common side effects
No common side effects listed.
Key warnings
You should not take this medicine if you have changes in your retina or vision.
The sections below are summarized in plain English from chloroquine's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Chloroquine phosphate works by killing the parasites that cause malaria and amebiasis. It stops the parasites from growing and multiplying in your body. For malaria caused by certain parasites, you may need to take another medicine with chloroquine.
Side Effects (from patient reports)
Based on 401 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for chloroquine, by number of reports
- Throwing up
Throwing up
49 reports
- Feeling sick to your stomach
Feeling sick to your stomach
48 reports
- Head pain
Head pain
41 reports
- High blood pressure
High blood pressure
41 reports
- Lung infection
Lung infection
40 reports
- Fever
Fever
40 reports
- Feeling tired
Feeling tired
37 reports
- Discomfort
Discomfort
37 reports
- Harm from different substances
Harm from different substances
36 reports
- Low oxygen levels
Low oxygen levels
32 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Serious Warnings
You should not take this medicine if you have changes in your retina or vision. You should not take this medicine if you are allergic to similar drugs.
Known Drug Interactions
7.4 Concomitant Use with Drugs that Induce Methemoglobinemia Concomitant use of ACZONE Gel, 7.5% with drugs that induce methemoglobinemia such as sulfonamides, acetaminophen, acetanilide, aniline dyes, benzocaine, chloroquine, dapsone, naphthalene, nitrates and nitrites, nitrofurantoin, nitroglycerin, nitroprusside, pamaquine, para‐aminosalicylic acid, phenacetin, phenobarbital, phenytoin, primaquine, and quinine may increase the risk for developing methemoglobinemia [see Warnings and Precautions ( 5.1 )] .
Mechanism: Both of these drugs can interfere with the way your red blood cells deliver oxygen to your body. Combining them increases the risk of a serious blood disorder.
( 7 ) 7.1 Drugs Prolonging QT Interval and Other Arrhythmogenic Drugs Hydroxychloroquine sulfate tablets prolongs the QT interval. There may be an increased risk of inducing ventricular arrhythmias if hydroxychloroquine sulfate tablets are used concomitantly with other arrhythmogenic drugs. Therefore, hydroxychloroquine sulfate tablets are not recommended in patients taking other drugs that have the potential to prolong the QT interval or are arrhythmogenic [see Warnings and Precautions (5.1) ].
Mechanism: Both of these drugs can change the electrical rhythm of your heart. Taking them together increases the risk of a dangerous irregular heartbeat.
Drugs That May Cause Methemoglobinemia When Used with LIDODERM Patients who are administered local anesthetics are at increased risk of developing methemoglobinemia when concurrently exposed to the following drugs, which could include other local anesthetics: Examples of Drugs Associated with Methemoglobinemia : Class Examples Nitrates/Nitrites nitric oxide, nitroglycerin, nitroprusside, nitrous oxide Local anesthetics articaine, benzocaine, bupivacaine, lidocaine, mepivacaine, prilocaine, procaine, ropivacaine, tetracaine Antineoplastic agents cyclophosphamide, flutamide, hydroxyurea,...
Mechanism: Both drugs can interfere with how your blood carries oxygen, which can lead to a dangerous health issue. Combining them makes this problem more likely to happen.
7 DRUG INTERACTIONS 7.1 Effects of Other Drugs on VEKLURY Due to potential antagonism based on data from cell culture experiments, concomitant use of VEKLURY with chloroquine phosphate or hydroxychloroquine sulfate is not recommended [see Warnings and Precautions (5.3) and Microbiology (12.4) ].
Mechanism: Chloroquine can block the antiviral effects of remdesivir, making it less powerful at treating the virus. This interaction was discovered in laboratory tests.
Examples of Drugs Associated with Methemoglobinemia: Class Examples Nitrates/Nitrites nitric oxide, nitroglycerin, nitroprusside, nitrous oxide Local anesthetics articaine, benzocaine, bupivacaine, lidocaine, mepivacaine, prilocaine, procaine, ropivacaine, tetracaine Antineoplastic agents cyclophosphamide, flutamide, hydroxyurea, isofamide, rasburicase Antibiotics dapsone, nitrofurantoin, para-aminosalicylic acid, sulfonamides Antimalarials chloroquine, primaquine Anticonvulsants phenobarbital, phenytoin, sodium valproate Other drugs acetaminophen, metoclopramide, quinine, sulfasalazine...
Mechanism: Chloroquine is known to cause a blood condition called methemoglobinemia, which makes it harder for your blood to carry oxygen. Taking it with other medications may increase the risk of this blood disorder.
This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.
Common Questions
What strength does this medication come in?
Can I use this to treat complicated malaria?
Can I use this to prevent malaria if the parasite is resistant to chloroquine?
How long should I continue taking this medication after leaving an area where malaria is common?
What should I do if I experience vision problems while taking this medication?
Can I take this medication if I have a known allergy?
How often should I take this medication for malaria prevention?
What is the adult dose for treating uncomplicated malaria?
Can children take this medication?
Does this medication cure malaria?
Does chloroquine interact with other medications?
What drug class is chloroquine?
What pregnancy or breastfeeding source fields are listed for chloroquine?
Related Medications in Antimalarial
Other drugs grouped near chloroquine - same-class peers and common alternatives.
acyclovir
Zovirax
Acyclovir is an antiviral medicine.
Compare with chloroquine →
albendazole
Albenza
Albendazole is a medicine that fights parasites.
Compare with chloroquine →
amphotericin B
Ambisome, Fungizone
Amphotericin B liposome is an antifungal medicine.
Compare with chloroquine →
anidulafungin
Eraxis
Eraxis is an antifungal medicine.
Compare with chloroquine →
atovaquone/proguanil
Malarone
Malarone is a drug used to prevent and treat malaria.
Compare with chloroquine →
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
FDA bioequivalence and label-record context for narrow therapeutic index medicines
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for chloroquine
The FDA label for chloroquine (sold under brand names such as Aralen) classifies it as a prescription-only medication in the Antimalarial class. This medicine can treat uncomplicated malaria caused by certain types of parasites. Labeling covers dosing, contraindications, and monitoring requirements derived from clinical trials.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 401 voluntary reports. The database also lists 5 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS shows a generic unit cost of $2.12.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.
Last updated: October 1, 2024
PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages