# What Phase 3 Acne Trials Actually Measure
When pharmaceutical companies test new acne treatments, they follow a strict process to ensure safety and effectiveness. Phase 3 clinical trials represent a critical stage in this journey, where researchers gather detailed information about how well a drug works and what side effects patients might experience.
Phase 3 trials are large-scale studies that involve hundreds of patients. These trials test different aspects of acne medications to determine whether they should be approved for public use. Understanding what these trials measure helps explain why some acne treatments make it to pharmacy shelves while others do not.
The primary focus of Phase 3 acne trials is measuring how effectively a treatment reduces acne lesions. Researchers count inflammatory papules, comedones, and other types of blemishes before and after treatment. For example, one Phase 3 trial of sarecycline involved 391 Chinese patients and measured the percentage reduction in facial inflammatory lesions over 12 weeks. Participants on sarecycline showed a 73.2 percent reduction in lesion count compared to 46.0 percent in the placebo group.
Trials also measure what dermatologists call the IGA score, which stands for Investigator’s Global Assessment. This is a standardized way to rate how clear a patient’s skin looks on a scale. Researchers track how many patients achieve clear or almost clear skin by the end of treatment. In one trial of a combination treatment containing clindamycin phosphate, adapalene, and benzoyl peroxide, approximately half of the participants achieved clear or almost clear skin with more than 70 percent reductions in lesion counts.
Safety monitoring is equally important in Phase 3 trials. Researchers carefully document any adverse events that occur during treatment. These can range from mild side effects like dryness and redness to more serious complications. For instance, a Phase 3 trial of denifanstat, a new acne medication, found that all treatment-related adverse events were mild or moderate in severity, with no serious adverse events reported.
The duration of Phase 3 trials varies depending on the medication being tested. Many acne trials last 12 weeks, which allows researchers to see how patients respond over a reasonable treatment period. Some trials include longer follow-up phases to assess whether improvements last after treatment ends or whether acne returns.
Phase 3 trials also measure how quickly a treatment works. Researchers note when patients first see improvements in their acne. In the sarecycline trial, noteworthy improvements appeared as early as week 3, suggesting rapid onset of action. This information helps doctors and patients understand what timeline to expect when starting a new treatment.
Different types of acne medications are tested differently. For hormonal treatments like spironolactone, researchers measure not just lesion reduction but also quality-of-life improvements. One randomized trial compared spironolactone plus benzoyl peroxide to doxycycline plus benzoyl peroxide in 133 women with moderate acne. The spironolactone group showed superior lesion reduction and better quality-of-life improvements.
Researchers also track how many patients complete the trial and whether anyone stops treatment due to side effects. This information reveals whether a medication is tolerable enough for real-world use. In the clascoterone trial involving 1421 patients, treatment-emergent adverse events occurred in about 18 percent of patients, with erythema and dryness being most common.
For some newer treatments, Phase 3 trials measure additional factors. For example, trials of self-administered acne injections measured whether patients could safely use the device at home without professional help. One study of 131 participants found that self-administered injections performed on par with provider-delivered ones, with no adverse events reported beyond minor bruising.
Phase 3 trials also establish the optimal dosing for a medication. Researchers compare different doses to find the lowest amount that produces meaningful results while minimizing side effects. In the self-injection trial, patients using a higher concentration sometimes responded faster, but even the lowest concentration proved effective.
The data collected in Phase 3 trials becomes the foundation for how medications are prescribed in real life. Regulatory agencies review these results to decide whether to approve a drug. They examine whether the benefits outweigh the risks and whether the medication works better than existing treatments.
Expert consensus studies represent another type of Phase 3 research in acne treatment. Rather than testing a new drug, these studies bring together experienced dermatologists to develop guidelines on how to use existing medications like isotretinoin. These experts rate their agreement with clinical statements using structured scales, and their consensus helps standardize treatment approaches across the medical field.
Phase 3 trials ultimately answer the question that patients and doctors care about most: does this treatment actually work, and is it safe? By measuring lesion reduction, safety profiles, quality of life, and treatment duration, these trials provide the evidence needed to bring new acne treatments to market and guide their use in clinical practice.
Sources
https://clinicaltrials.gov/study/NCT07296523
https://pmc.ncbi.nlm.nih.gov/articles/PMC12691598/
https://beautymatter.com/articles/the-glp1-effect-acne-market
