Inclusion Criteria:
* Patient has given written informed consent to participate in the study prior to admission to the study;
* Female patients aged between 16 and 35 years old, inclusive;
* History of regular menstrual cycles, occuring between every 21 to 35 days;
* Clinical history compatible with the diagnosis of primary dysmenorrhea;
* Self-reported history of ≥ 4 painful cycles, with moderate or severe menstrual cramps, in the six (06) months prior to selection for the study.
Exclusion Criteria:
* Diagnosis of secondary dysmenorrhea;
* History of non-response to treatment with non-steroidal anti-inflammatory drugs (NSAIDs) to relieve menstrual cramps;
* Onset of primary dysmenorrhea after starting to use oral contraceptives;
* Use of oral contraceptives for \< 3 months prior to study selection;
* Use of an intrauterine device (IUD), hormonal implants or contraceptive injections in the last six (06) months;
* Previous diagnosis or physical examination findings and/or clinical and/or surgical history that may indicate the presence of endometriosis, pelvic inflammatory disease, adenomyosis, mullerian duct malformation, uterine fibroma, cystic ovary and/or pelvic varicocele;
* History of recurrent pelvic and/or lower abdominal pain outside the menstrual period;
* Presence of known allergy or hypersensitivity to the components of the drugs used during the clinical trial;
* History of hypersensitivity reactions, such as asthma attacks or other types of allergic reactions, to acetylsalicylic acid or other NSAIDs;
* History or diagnosis of peptic/hemorrhagic ulcer;
* History of gastrointestinal bleeding or perforation related to the use of NSAIDs;
* Presence of compromised bone marrow function or diseases of the hematopoietic system;
* Diagnosis of acute intermittent hepatic porphyria;
* Diagnosis of congenital deficiency of glucose-6-phosphate dehydrogenase (G6PD);
* Diagnosis of untreated angle-closure glaucoma;
* Presence of mechanical stenosis in the gastrointestinal tract;
* Diagnosis of megacolon and/or paralytic or obstructive ileus;
* Diagnosis of myasthenia gravis;
* Treatment with psychoactive drugs (such as, for example, antidepressants, antipsychotics, etc.) in the 30 days prior to selection for the study;
* Participants with a history of alcohol or illicit drug use disorder in the last two (02) years;
* Participants with a current medical history of cancer and/or cancer treatment in the last five (05) years;
* Presence of any serious illness, at the discretion of the investigator;
* Any finding of clinical observation (clinical/physical evaluation) or laboratory condition that is interpreted by the investigating physician as a risk to the participation of the research participant in the clinical trial or presence of uncontrolled chronic disease(s);
* Participants who are pregnant, nursing or planning to become pregnant;
* Disagreement with the use of a known effective barrier contraceptive method, unless using a stable oral contraceptive for three months or more (which must be maintained throughout the study), or surgically sterile or who expressly declare themselves exempt from risk of pregnancy for not exercising sexual practices or exercising them in a non-reproductive manner;
* Participation in a clinical research protocol in the last 12 months (CNS Resolution 251, of August 7, 1997, item III, subitem J), unless the investigator judges that there may be a direct benefit to it;
* Presence of any condition that, at the discretion of the investigator, makes the patient unfit to participate in the study.
