What is Aralen (chloroquine), and how does it work (mechanism of action)?

Chloroquine, brand name Aralen, is an anti-malarial drug. It is similar to hydroxychloroquine (Plaquenil), and is useful in treating several forms of malaria as well as amebiasis that has spread outside of the intestines. Its mechanism of action is unknown; however, malarial parasites invade human red blood cells, and chloroquine may prevent malarial parasites from breaking down (metabolizing) hemoglobin in human red blood cells.  Chloroquine is effective against the malarial parasites Plasmodium vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum.

Is Aralen available as a generic drug?

Yes, chloroquine is available in generic form.

What are the uses for Aralen?

Aralen is used for treating:

  • Acute attacks of malaria due to P. vivax, P. malariae, P. ovale, and susceptible strains of P. falciparum
  • Extraintestinal amebiasis

Aralen is not effective for malaria prevention. It suppresses malaria infection, stops acute attacks, and lengthens the time between treatment and relapse.

It’s off-label use (non-FDA approved use) is for the treatment of porphyria cutanea tarda.

What are the side effects of Aralen?

Common side effects include

Other, rare side effects

Possible serious effects

Other adverse reactions and side effects of Aralen

  • There have been rare reports of severe skin reactions such as erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis, and exfoliative dermatitis.
  • Chloroquine may precipitate a severe attack of psoriasis in patients with psoriasis and may worsen porphyria. Chloroquine should not be used in these conditions unless the benefit to the patient outweighs the potential risks.
  • People with retinal or visual field changes should not use chloroquine unless it is absolutely necessary.
  • Some strains of P. falciparum are resistant to chloroquine and hydroxychloroquine. Chloroquine resistance is widespread.
  • Chloroquine should not be used for treatment of P. falciparum infections from areas of chloroquine resistance or malaria occurring in patients where chloroquine prophylaxis has failed.
  • Patients infected with a resistant strains of plasmodia should be treated with another antimalarial drug.
  • Retinopathy, maculopathy, irreversible retinal damage, as well as macular degeneration have been reported. Retinopathy from chloroquine may be dose related. Initial and periodic eye examinations are recommended during prolonged treatment. Chloroquine should be discontinued immediately if there are changes in vision.
  • Chloroquine may cause acute extrapyramidal disorders (abnormal, uncontrollable body movements) that usually resolve after treatment is stopped.
  • Patients should be observed for evidence of muscular weakness. If weakness occurs treatment should be stopped.
  • Fatalities have occurred in children from accidental ingestion of small doses of chloroquine. Chloroquine should be kept out of the reach of children.


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What is the dosage for this Aralen?

  • For acute malaria attacks in adults the initial dose is 1 g followed by an additional 500 mg after 6 to 8 hours, then 500 mg 24 and 48 hours after the first dose.
  • The dose for treating children is 10 mg/kg for the first dose then 5 mg/kg daily for 2 days, starting 6 hours after the first dose.
  • The dose for treating intestinal amebiasis is 1 g daily for two days, followed by 500 mg daily for at least two to three weeks.

Chloroquine usually is combined with an effective intestinal amebicide.

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Which drugs or supplements interact with this medication?

  • Antacids and kaolin can reduce absorption of chloroquine.  Administration of this drug and these agents should be separated by at least 4 hours.
  • Cimetidine (Tagamet) can block the breakdown of chloroquine, increasing its blood levels. This combination should be avoided.
  • Chloroquine significantly reduces blood levels of ampicillin. Ingestion of ampicillin and chloroquine should be separated by at least two hours.
  • Chloroquine may increase cyclosporine blood levels. Cyclosporine blood levels should be monitored and, if necessary, chloroquine should be stopped.
  • Combining chloroquine and mefloquine may increase the risk of seizures.
  • Chloroquine can reduce the antibody response to primary immunization with intradermal human diploid-cell rabies vaccine.


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Is this drug safe to use during pregnancy or while breastfeeding?

  • There are no studies evaluating the safety and efficacy of chloroquine in during pregnancy. If you are pregnant this drug should be avoided unless it is necessary and the benefit outweighs the risk.
  • Chloroquine is excreted in breast milk.

What else should I know about this medication?

  • This drug is available as 250mg and 500 mg tablets.
  • Keep this medication stored at room temperature, between 15-30 C (59-86 F).
  • The FDA approved chloroquine in October 1949.

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Medically Reviewed on 9/30/2019


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