FDA Warns Against Using Quinine for Leg Cramps

Author: U.S. FDA
Published: 2010/07/08 - Updated: 2025/08/05
Publication Type: Announcement
Category Topic: Recalls, Warnings and Advisories - Academic Publications

Page Content: Synopsis - Introduction - Main - Insights, Updates

Synopsis: This article reports on an FDA warning against the off-label use of Qualaquin (quinine sulfate), an antimalarial medication, to treat nighttime leg cramps following documented cases of serious adverse effects. The information is authoritative because it comes directly from the U.S. Food and Drug Administration's official safety communication, making it highly reliable for healthcare professionals and patients seeking accurate medical guidance.

The article details how a review of the FDA's Adverse Event Reporting System found 38 cases of serious side effects between 2005 and 2008, including life-threatening blood disorders that resulted in permanent kidney damage, hospitalizations, and two deaths. This regulatory warning is particularly valuable for individuals with disabilities and seniors who may be more vulnerable to medication misuse or who frequently experience leg cramps, as it provides crucial safety information about a drug that was never approved for this common condition despite being prescribed off-label by some healthcare providers - Disabled World (DW).

Introduction

FDA warns of risks with unapproved use of malaria drug Qualaquin. Serious side effects reported when used to treat or prevent night time leg cramps.

Main Content

The U.S. Food and Drug Administration has warned that the unapproved use of the malaria drug Qualaquin (quinine sulfate) to treat night time leg cramps has resulted in serious side effects and prompted the manufacturer to develop a risk management plan aimed at educating health care professionals and patients about the potential risks. Qualaquin is not FDA-approved to treat or prevent night time leg cramps.

A review of reports submitted to the FDA's Adverse Event Reporting System (AERS) between April 2005 and Oct. 1, 2008, found 38 U.S. cases of serious side effects associated with the use of quinine, the active drug in Qualaquin.

Quinine use resulted in serious and life-threatening reactions in 24 cases, including low level of platelets in the blood (thrombocytopenia), and hemolytic uremic syndrome/thrombotic thrombocytopenic purpura, a blood disorder that results in clots in small blood vessels around the body that can be accompanied by kidney impairment.

In some patients, these side effects resulted in permanent kidney impairment and hospitalization. Two patients died. Most of those reporting serious side effects took the drug to prevent or treat leg cramps or restless leg syndrome.

The risk management plan, called a Risk Evaluation and Mitigation Strategy (REMS), requires that patients be given a Medication Guide explaining what Qualaquin is and is not approved for, as well as the potential side effects of the drug. The company is also required to issue a Dear Health Care Provider Letter warning of the potential risk of serious and life-threatening blood-related (hematologic) reactions.

"Health care professionals and patients should be aware that FDA has not approved the use of Qualaquin for the treatment or prevention of night time leg cramps," said Edward Cox, M.D., M.P.H., director, Office of Antimicrobial Products in the FDA's Center for Drug Evaluation and Research. "FDA has received reports that some patients have developed serious side effects when taking quinine for night time leg cramps."

Qualaquin was approved by the FDA in August 2005 to treat uncomplicated malaria caused by the parasite Plasmodium falciparum, an infection that can be life-threatening if untreated. According to the U.S. Centers for Disease Control and Prevention, about 1,500 cases of malaria are diagnosed in the United States each year, primarily resulting from travel abroad. Qualaquin is marketed by Philadelphia-based AR Scientific. Health care professionals and patients may report serious adverse events (side effects) to the FDA's MedWatch Adverse Event Reporting program online, by regular mail, fax, or phone.

Insights, Analysis, and Developments

Editorial Note: The FDA's decisive action in implementing a Risk Evaluation and Mitigation Strategy for Qualaquin demonstrates the critical importance of regulatory oversight in preventing the dangerous misuse of prescription medications. While leg cramps can be debilitating, particularly for older adults and those with mobility limitations, this case underscores why patients must work closely with their healthcare providers to find safe, evidence-based treatments rather than relying on unapproved uses of powerful medications that carry potentially fatal risks - Disabled World (DW).

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Citing and References

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Cite This Page: U.S. FDA. (2010, July 8 - Last revised: 2025, August 5). FDA Warns Against Using Quinine for Leg Cramps. Disabled World (DW). Retrieved October 30, 2025 from www.disabled-world.com/medical/recalls/malaria-cramps.php

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