Unapproved Qualaquin Use Is Risky

FDA Issues New Warning About Using Malaria Drug Qualaquin to Treat or Prevent Nighttime Leg Cramps

Medically Reviewed by Laura J. Martin, MD on July 13, 2010
From the WebMD Archives

July 13, 2010 -- The FDA has issued a new warning about the use of the malaria drug Qualaquin (quinine sulfate) to prevent or treat nighttime leg cramps, stating that it can cause serious side effects.

The adverse side effects prompted Philadelphia-based AR Scientific, which markets the drug, to develop a risk management plan aimed at educating the public and health care professionals about the potential risks, according to the FDA.

Qualaquin has never been approved by the FDA to prevent or treat nighttime leg cramps. At least 38 cases of serious side effects from taking the drug were reported between April 2005 and Oct. 1, 2008, the FDA says in a news release.

Qualaquin Linked to Dangerous Blood Disorders

The FDA told people on Dec. 12, 2006, not to use quinine for leg cramps, citing potentially deadly side effects.

It said then that Qualaquin could be used to treat certain types of malaria, but it added that the unapproved use of quinine is risky.

Between April 2005 and Oct. 1, 2008, quinine use resulted in serious and life-threatening reactions in 24 cases, including low levels of platelets in the blood and blood disorders (hemolytic uremic syndrome, thrombotic thrombocytopenic purpura) that result in clots in small blood vessels around the body that can be accompanied by kidney impairment.

According to the FDA, two people died from side effects in the 2005-2008 period, and some patients had permanent kidney damage and required hospitalization.

The FDA says most of those who reported serious side effects took the drug to prevent or treat leg cramps or restless legs syndrome.

“Health care professionals and patients should be aware that the FDA has not approved the use of Qualaquin for the treatment or prevention of night time leg cramps,” Edward Cox, MD, MPH, director of the Office of Antimicrobial Products in the agency’s Center for Drug Evaluation and Research, says in the news release.

Reporting Qualaquin Side Effects

The risk management plan developed by AR Scientific, called a Risk Evaluation and Mitigation Strategy, or REMS, requires that patients be given a medication guide explaining what Qualaquin is, and is not, approved for. It also outlines potential side effects.

The company is required to issue a letter to health care providers warning of the potential risk of serious and life-threatening blood-related reactions.

The FDA approved Qualaquin in August 2005 to treat uncomplicated malaria caused by the parasite Plasmodium falciparum, an infection that can be life-threatening if not treated.

Health care professionals and patients may report serious side effects online to the FDA’s MedWatch Adverse Event Reporting program, by regular mail, phone, or fax. Side effects can be reported by regular mail with a pre-addressed FDA form, available at the same web site, or by fax to 800-FDA-0178 or phone to 800-332-1088.

More information is available at, and a FDA consumer article is available at

FDA's Advice on Qualaquin

The FDA offers this advice for consumers:

  • If you take Qualaquin for nighttime leg cramps, discuss other treatment options with your doctor.
  • Contact your doctor immediately if you experience easy bruising, severe nose bleeding, blood in your urine or stools, bleeding gums, or the appearance of unusual purple, brown, or red spots on the skin.
  • Read the medication guide provide by the pharmacy when you pick up a prescription for Qualaquin.
  • Report any side effects to the MedWatch Adverse Event Reporting Program.

The FDA says the medication guide spells out what Qualaquin is approved and not approved for, as well as its potential side effects.

The FDA had previously warned Americans in late 2006 not to use quinine for leg cramps. It said then that it had received 665 reports of serious adverse events linked to quinine, including 93 deaths.