The goal of this clinical trial is to compare 1% and 3% diclofenac gel (DARE-PDM1) to placebo in women with symptomatic primary dysmenorrhea. The main question it aims to answer are:

Is DARE-PDM1 1%, 3% diclofenac gel systemically safe? What are the systemic levels of DARE-PDM1 1%, 3% diclofenac gel in plasma and vaginal fluid following 1 dose and 3 doses.

Participants will be seen for routine safety evaluations and complete a daily diary recording dysmenorrhea associated pain.

Inclusion Criteria:

• Females ages 18- 50 years old (inclusive)
• Self-assessment of historic dysmenorrhea associated pain level of ≥ 5 on a scale of 0 - 10 in at least one of the following anatomic sites: pelvic/vaginal pain, low back pain, while not using NSAIDs or hormonal contraception.
• Non-pregnant status
• If applicable, agrees to be sexually abstinent and place nothing in the vagina during the 120 hours between visits 3 and 8 and the 3-day period of the multiple dose regimen.
• Agrees to use adequate non-hormonal birth control during the trial (e.g. study provided male condoms without nonoxynol-9 lubricant, tubal sterilization, heterosexual abstinence) (Because hormonal birth control is a known off label treatment for dysmenorrhea, if the participant is on hormonal birth control other than Depo-Provera contraceptive injection, she agrees to discontinue it and have at least one spontaneous intervening menses before the start of the study period. If using Depo Provera, has not had an injection within the 4 months before Visit 1 and must have had a spontaneous menses prior to visit 2.)
• Provides informed consent for participating in the trial
• Willingness to use only study-provided oral paracetamol as rescue pain medication for dysmenorrhea, if needed according to investigator's instruction.
• Patient is fluent in the English language.
• Patient is capable of understanding and complying with the protocol and agrees to sign the informed consent document.
• Patient has had a cervical screen performed within five years prior to Visit 1 and can provide documentation indicating normal test results consistent with Australian Health guidelines. If the patient cannot provide documentation, a cervical screen will be performed at Visit 1. Patients with abnormal findings will be excluded from study participation and be referred for follow-up medical care as appropriate.

Exclusion Criteria:

• Positive pregnancy test
• Unwilling or unable to comply with protocol
• Allergic to diclofenac or other non-steroidal anti-inflammatory drugs (NSAIDs)
• Patients with severe liver, kidney or heart failure
• After the use of aspirin or other nonsteroidal anti-inflammatory drugs, asthma, nasal polyps, angioedema and urticaria have occurred in the past
• Current active peptic ulcer bleeding or perforation
• Have a history of significant upper gastrointestinal disease
• Have a chronic pain syndrome other than dysmenorrhea which could confound preliminary efficacy data (e.g., chronic low back pain unrelated to menses)
• Have a positive Sexually Transmitted Infection (STI) test at screening for Chlamydia trachomatis or Neisseria gonorrhea

A decision has not yet been made on when or what IPD to share when available.