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The Fascinating Mystery of “The Toxic Lady”

  • Writer: FibonacciMD
    FibonacciMD
  • Apr 1
  • 6 min read

Updated: Jun 17

The Toxic Lady: A Medical Mystery That Left More Questions Than Answers

A California ER was thrown into chaos when multiple staff members collapsed after treating a patient. Dubbed "The Toxic Lady," this case remains one of medicine’s strangest unsolved mysteries. Was it a deadly chemical reaction—or something even more perplexing?

Medical News

Last updated May 27, 2025


the mystery of the toxic lady

On February 19, 1994, ambulance personnel in Riverside, California, were called to attend to a 31-year-old female, Gloria R., who had difficulty breathing and an irregular heartbeat. There had been a history of nausea and vomiting for a few days, and the patient had terminal cervical cancer. She was taken to the Riverside General Hospital Emergency Department (ED) and arrived there semiconscious, sluggishly responsive, with shallow breathing and a rapid heartbeat.  She soon deteriorated, and the ED staff started cardiopulmonary resuscitation. The patient reportedly vomited after intubation. The staff noted an ammonia smell emanating from the patient, and one staff member reported a fruity, garlic odor emanating from the patient’s mouth. Staff also described her body as having an oily, shimmering sheen. A nurse started an intravenous line, and while drawing blood noted white or manila crystals in the blood, which was also verified by other staff.  That nurse then fainted, and a doctor took her place, who then herself lost consciousness and started having convulsions.  More staff members became ill, and the emergency department chairman ordered the ED evacuated except for staff treating Gloria R., who by then had started donning HAZMAT equipment. The patient was declared dead approximately 35 minutes after arrival. 


A HAZMAT (hazardous materials)  emergency was declared, and a HAZMAT team tested for toxic gases in the ED and found none. Twenty-three hospital employees were affected with various different acute ailments, including dizziness, headache, respiratory irritation, tearing, nausea, and vomiting. Six staff members were ill enough to require hospitalization. Some staff ended up having longer-lasting symptoms such as tremors, muscle spasms, memory lapses, and shortness of breath. The mystery was: how could a possible toxin affect so many staff members and not leave behind any traces? Also, why were some staff affected and some not? 


An autopsy was performed under strict HAZMAT protocols, and the conclusion was that there were no indications of toxic, volatile, or hazardous vapors associated with specimens of Gloria R.’s tissues and body fluids, or in the air samples from the ED. The cause of death was listed as dysrhythmia caused by renal failure. 


Due to a lack of any specific toxicological findings, the California Department of Health Services released a report which concluded that the incident was most probably due to an outbreak of mass sociogenic illness (also known as mass psychogenic illness and was previously called mass hysteria). Needless to say, this conclusion was not universally accepted.


An Alternative Explanation Is Suggested

Biological materials and the patient’s files were sent to the Forensic Science Centre at Livermore National Laboratories in California, where, after an analysis, they postulated an alternative explanation. 


They discovered a breakdown product of dimethylsulfoxide (DMSO), called dimethyl sulfone (DMSO2) in Gloria R.’s blood and bile samples. DMSO is a liquid solvent derived from wood pulp that can be absorbed through the skin and has been used in medicine for a number of different indications. It has been used as a topical remedy for musculoskeletal and arthritis pain and has continued to be used as a home remedy. DMSO has also been found to have antianxiety and antipsychotic effects. It is FDA- approved for treating pain in interstitial cystitis (painful inflammation of the bladder). DMSO has been used as an antibacterial agent and has even been used in the therapy of cervical cancer. It also has been used to prevent skin damage if a chemotherapy drug leaks out of an intravenous line.  It fell somewhat into disfavor when the FDA discovered that the use of DMSO caused serious eye problems in test animals, and they limited research using the drug. 


As the patient was in renal failure and DMSO is excreted by the kidneys, if Gloria R. was using DMSO, it would have accumulated in her body. There is no other direct evidence that Gloria R. was using DMSO, except for the breakdown product dimethyl sulfone (DMSO2) found in blood and bile. Another breakdown product of DMSO, dimethyl sulfide ((CH3)2S) has a garlicky odor, which one of the nurses in this case stated was present. 


Livermore Laboratory scientists postulated that the addition of supplemental oxygen used in the resuscitation allowed dimethyl sulfone (DMSO2), to become oxidized to dimethyl sulfate (DMSO4), which contains four oxygen molecules). Dimethyl sulfate has been classified as a chemical warfare agent and can be inhaled or absorbed through the skin. Dimethyl sulfate can cause dizziness, prostration, headache, convulsions, coma, pulmonary irritation, lung damage, and slow heart rate (bradycardia). Many of the symptoms ascribed to dimethyl sulfate were seen in the affected hospital staff, and the doctor who initially convulsed and also required a ventilator due to irregular breathing, had health problems for a prolonged period after the episode, including hepatitis and pancreatitis.


The Livermore Laboratory scientists felt that the reason crystals were observed in initial blood samples was due to the conversion of DMSO in those blood samples to DMSO2. Conversion of DMSO2 to dimethyl sulfate resulted in the crystals' disappearance later on. They demonstrated experimentally that at body temperature DMSO2 completely dissolved in heated Ringer’s lactate solution, but at a cooler 72 degrees F it precipitated out into crystals.  They postulated that the DMSO2 in the room-temperature blood sample tubes crystallized, which was what was witnessed by the ED staff. Later, the crystals disappeared as the DMSO2 was converted to dimethyl sulfate, which does not crystallize. It was felt the ambulance crew did not get affected due to the length of time it took for the administered oxygen to convert the DMSO2 to dimethyl sulfate. 


Comments: 

This case represents one of a healthcare worker’s major fears: unexpected exposure from a patient to a toxin that can also injure the health care worker. The initial conclusion of mass sociogenic illness is difficult to accept given that convulsions occurred in the physician, who then required mechanical ventilation, as well as the documentation of manila-colored material floating in the patient’s blood. It is possible that some of the later victims, after seeing their colleagues affected, did have a psychogenic reaction. Why some staff were affected and some not is still a mystery and does give some credence to the mass sociogenic illness theory, but it may be the result of actual levels of and timing of the exposure, or just individual variation of response to a toxin. There is no direct evidence that Gloria R. was actually using DMSO, which is problematic. However, the oily body sheen, garlic odor, severity of some of the symptoms, and finding dimethyl sulfone in blood and bile samples lend some support that its conversion to dimethyl sulfate from oxygen used in treatment could be the cause of this mysterious episode. At the time, Gloria R. was dubbed “The Toxic Lady” by the media reporting this story.





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