Major US medical authorities, including the Infectious Diseases Society of America, the American Academy of Neurology, and the National Institutes of Health, have stated there is no convincing evidence that Borrelia is involved in the various symptoms classed as CLD, and particularly advise against long-term antibiotic treatment as it is ineffective and potentially harmful.[1][10][11][4] Prolonged antibiotic therapy presents significant risks and can have dangerous, even deadly, side effects.[25] Randomized placebo-controlled studies have shown that antibiotics offer no sustained benefit in people with chronic Lyme, with evidence of both placebo effects and significant adverse effects from such treatment.[26] Many people who believe that they have chronic Lyme have fibromyalgia.[7][8] Fibromyalgia can be difficult to treat, and antibiotics do not work at all for fibromyalgia.[6] A pressure group called the International Lyme and Associated Diseases Society (ILADS)[27] says that the persistence of B. burgdorferi may be responsible for manifestations of chronic Lyme disease symptoms.