Efficacy of Calendula gel on the Healing of Chronic Wounds: An Open–Label Randomized Controlled Trial

Abstract

Introduction and objective: The management of chronic wounds remains a clinical challenge in modern healthcare due to their delayed healing process and increased risk of recurrent infections, which demand substantial healthcare resources. Recently, integration of herbal remedies with conventional medicine has gained attention, especially herbs with anti–inflammatory and wound healing properties. Calendula officinalis L. (pot marigold) is a medicinal plant with strong therapeutic potential, containing bioactive compounds such as flavonoids, lutein, saponins, and triterpenoids that exhibit antioxidant, anti–inflammatory, and tissue–regenerating effects. This study aimed to evaluate the efficacy of Calendula gel in combination with standard care for chronic wound healing using the Pressure Ulcer Scale for Healing (PUSH) score as the primary outcome, and to assess the safety of the herbal formulation.

Methods: This open–label randomized controlled trial was conducted at Tao Ngoi Hospital and its affiliated network in Sakon Nakhon Province, Thailand. A total of 46 patients with chronic wounds were divided into two groups using block randomization with a block size of 4. Both groups underwent daily wound cleansing following standard protocols. Afterwards, the intervention group (n = 23) received topical application of 4% w/v Calendula gel, prepared from German-origin mother tincture, once daily for seven days, while the control group (n = 23) received placebo gel. Daily assessments of wound status and pain intensity were conducted over a 7-day period using the PUSH score and Numerical Rating Scale (NRS), and any adverse events were monitored and documented. Data were analyzed using descriptive statistics, including mean, standard deviation, and percentage. For clinical outcomes, a linear mixed-effects model was employed to analyze the daily trends of PUSH scores and compare percentage changes of PUSH scores between groups. Pain scores were analyzed using a paired t-test for intra-group comparisons and an independent t-test for inter-group comparisons.

Results: Throughout the 7-day follow-up period, both the experimental and control groups showed a continuous reduction in PUSH scores, reflecting progressive wound healing over time. However, the group receiving calendula gel demonstrated a faster and greater reduction in scores compared to the control group, with noticeable differences emerging around days 4–5 and becoming more pronounced during days 5–7. When considering changes from baseline, the experimental group showed a statistically significant reduction from day 5, whereas the control group showed significant improvement only on days 6 and 7. Furthermore, comparisons of percentage change between groups revealed statistically significant differences on days 5 and 6, supporting that calendula gel combined with standard treatment enhances wound healing more effectively than standard wound care plus placebo gel. The experimental group also demonstrated a more rapid and sustained wound recovery trend, with no reported adverse events or product-related side effects throughout the follow-up period. Meanwhile, NRS scores for pain were not significantly different between groups throughout the follow-up period (p > 0.05). These findings suggest that calendula gel may play a role in accelerating tissue repair and reducing healing time when used in conjunction with standard care.

Discussion: The use of Calendula gel alongside standard care significantly promoted chronic wound healing and may be particularly beneficial in settings with limited healthcare resources. This finding aligns with the principles of integrative medicine, which blends evidence–based modern medicine with traditional therapies to enhance clinical outcomes. Calendula–based products are also low–cost and easily accessible, making them well-suited for use in general practice. Our findings are consistent with previous clinical trials conducted in Europe and Latin America, which reported positive outcomes of topical Calendula officinalis in wound healing.  Additionally, the absence of any adverse reactions in this study supports the safety profile of the gel, making it a viable option for vulnerable populations such as the elderly, diabetic patients, and those with compromised immunity.

Conclusions and Recommendations: Calendula gel was found to be safe and effective when used as an adjunct to standard wound care in patients with chronic wounds. The results support the development of reliable herbal–based interventions for clinical use. Further research should involve larger sample sizes, various types of chronic wounds (e.g., diabetic ulcers, pressure ulcers), and long-term follow-up to confirm the consistency of these outcomes in diverse healthcare contexts. Such evidence could serve as a foundation for incorporating Calendula gel into national public health policy as an alternative or adjunctive therapy in wound care.

Key words: Calendula gel, chronic wounds, PUSH score, wound healing, randomized controlled trial