The chloroquine-induced suffering refers to severe eye impairment, including blindness, caused by long-term use of the antimalarial drug chloroquine. Although originally developed for short-term treatment, chloroquine’s indications in Japan were expanded during the 1950s‒60s to include nephritis, rheumatoid arthritis, and asthma, and the drug was widely marketed by pharmaceutical companies. Both the government and the pharmaceutical industry ignored warnings about its toxicity for many years, and the number of victims is estimated at between 1,000 and 2,000.
| 1934 | Synthesized by Germany’s Bayer AG; effective against malaria but highly toxic, leading to development halt |
| 1943 | Used by American companies for short-term treatment as a specific cure for malaria |
| 1958 | Sales begin in Japan as a treatment for nephritis and rheumatism. In 1961, large-scale sales begin as a specific treatment for chronic nephritis. |
| 1958 | Health damage occurs (around 1958–1974) |
| 1971 | Health damage caused by chloroquine becomes a social issue |
| 1975 | First lawsuit filed |
| 1980 | Second lawsuit filed |
| 1982 | First case won, but the government is not held responsible |
| 1987 | Second case won; again, the government is not found liable |
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1. Development and domestic use in Japan
Chloroquine was first synthesized by Bayer in Germany in 1934, but its development was suspended because of its strong toxicity. During Second World War, American researchers revived it as a short-term treatment for malaria, using it as a substitute for quinine in tropical war zones. After the war, although malaria control became less urgent internationally, Japanese pharmaceutical companies began domestic marketing chloroquine in 1958—not for malaria but to treat nephritis. Its approved indications were subsequently expanded to include chronic rheumatoid arthritis, bronchial asthma, and even epilepsy. By 1961, it was sold in large quantities as a specific treatment for chronic nephritis and widely prescribed, and the first reports of chloroquine retinopathy—severe retinal damage causing visual-field constriction and blindness–began to appear.
2. Warnings abroad and official neglect in Japan
In the United States, chloroquine continued to be used for malaria, but under strict restrictions. Clinical studies there had already confirmed its potential ocular toxicity, and long-term administration was explicitly contraindicated. The U.S. Food and Drug Administration instructed pharmaceutical companies to distribute safety warnings about eye damage to doctors. In Japan, however, despite similar warnings, neither the Ministry of Health and Welfare (MHW) nor pharmaceutical companies took preventive action. Some pharmaceutical companies promoted chloroquine as “safe for long-term use because of its low toxicity.” It was later revealed that in 1965, a division chief within the MHW who had personally taken chloroquine for nephritis discontinued its use after learning of serious side effects reported in the United States; however, still no action was taken at ministerial level. The MHW did not order the inclusion of retinopathy warnings in the package insert until 1969, and manufacturing finally ceased only in 1974.
3. Prolonged litigation and social recognition
In 1971, one patient personally appealed to the Minister of Health for relief, and major newspapers publicized the case, transforming the chloroquine issue into a national controversy. Although the minister did not respond to the appeal, media coverage enabled many previously unrecognized victims to realize that their blindness and visual impairment might have been caused by chloroquine. In 1972, victims formed a victims’ association and began negotiations with four pharmaceutical companies. After three and a half years of unsuccessful negotiations, without apology or adequate compensation, the group filed lawsuits in 1975 against both the government and the companies. As few doctors agreed to testify for the plaintiffs, some victims also sued medical institutions that refused cooperation as co-defendants, making the litigation unusually complex and protracted. During the trials, it became clear that the scientific paper originally cited to justify chloroquine’s effectiveness for nephritis lacked methodological credibility. In 1976, an official review concluded that chloroquine was not effective for nephritis. In 1982, the district court ruled in favor of the plaintiffs, recognizing the responsibility of the government, the pharmaceutical companies, and the involved doctors. However, on appeal, higher courts overturned the ruling with respect to the government, and the Supreme Court upheld this reversal in 1995—approximately forty years after the initial harm occurred. Although the final decision denied government responsibility, victims received compensation of approximately 50 million yen per person, an unusually high amount at the time. Many victims, however, died before the judgment was reached.
References
- The Pharmaceutical and Medical Device Regulatory Science Society of Japan Pharmacopoeia Association (2012). 『知っておきたい薬害訴訟の実際――企業リスクの最小化を目指して』. Yakuji Nippo. (ISBN 4840813795).
- The Pharmaceutical and Medical Device Regulatory Science Society of Japan Pharmacopoeia Association (2011). 『知っておきたい薬害の知識』Jiho. (ISBN 4840741743).