Premenstrual syndrome is characterized by pain and related symptoms that negatively affect women’s quality of life. Our aim was to evaluate the safety and effectiveness of a specific oral fixed dose combination of naproxen 220 mg + paracetamol 300 mg + pamabrom 25 mg in tablet form. A prospective, open-label, multicenter, uncontrolled, observational post-marketing study was conducted from December 2017 to December 2019 consisting of 270 women over 18. The primary outcome was the number and severity of adverse effects. Secondary outcomes were pain intensity, number and intensity of other premenstrual symptoms, and the proportion of patients with a pain score reduction of at least 50%. The mean age of participants was 28.9 ± 8.8 years. We found that 8 women (3%) experienced adverse events, namely headache (5/8), gastritis (2/8) dyspepsia (1/8), diarrhea (1/8), and nausea (1/8). In three of the eight women, the study was discontinued due to adverse effects. Pain intensity was reduced (−4.5, 95%CI; −5, −4, p < 0.001). The proportion of patients with pain reduction of at least 50% was 70.7%. The study results suggest that the combination of drugs used in this formulation is safe and effective for premenstrual symptoms.