In Brazil, Imunoparvum R° is used as an immunomodulator. It is commercialized in 2 ml ampoules containing 2 mg of Propionebacterium acnes (formerly known as Corynebacterium parvum)/ml, in a 0.5 % phenol and 0.85% sodium chloride solution. High therapeutic power associated to minimum side effects is a great challenge to the pharmaceuticalindustry. Research results have shown that Imunoparvum R° induces side effects in humans and animals, probably because of its phenol content (SOUSA, 1993; RODRIGUES, 2001). The objective of this study was to determine the phenol content of lyophilized and non-lyophilized Imunoparvum R° and to compare their side effects in mice. It was demonstrated that the lyophilization process reduces the phenol content and the side effects of Imunoparvum R°, when compared to the commercialized Propionebacterium acnes suspension
