Background: Pegylated granulocyte colony stimulating factor (PEG-G-CSF) is used as prophylaxis to reduce the risk of neutropenic fever, as a complication of chemotherapy. Bone pain is one of this drug complications. Although we do not have a standard treatment for controlling the secondary pain due to PEG-G-CSF, the combination of Naproxen and Loratadine has shown good results in several studies. Objectives: The purpose of this study was to compare the non-inferiority of Acetaminophen-Loratadine combination due to its lower complications with the known Naproxen-Loratadine combination in patients with cancer. Methods: Total of 200 patients with solid tumor and lymphoma were randomly assigned to the groups of A (Naproxen and Loratadine), and B (Acetaminophen and Loratadine), and the treatment were applied. During the chemotherapy weeks, after each chemotherapy session, pain scores were evaluated on a pain questionnaire according to the designed schedule. Finally both groups were compared. Results: The median age of patients in the Acetaminophen group was significantly higher than the Naproxen group (P < 0.001). The mean pain score of patients before chemotherapy was 1.07 in the Naproxen group and 1.67 in the Acetaminophen group. There was a statistically significant difference in patients' average pain between the two groups before the start of chemotherapy (P < 0.001). After controlling the effect of age, sex, and baseline pain, it was observed that the mean pain score in all courses in the Acetaminophen group was higher than the Naproxen group (P = 0.044). Conclusions: By controlling the effects of age, sex, and baseline pain, Naproxen in the second and subsequent courses of treatment was significantly better than Acetaminophen in reducing pain.