Ginger uses several mechanisms to relieve pain, such as inhibition of prostaglandins through COXs and LOXs pathways, antioxidant activities, inhibition of the nf-kB transcription factor, and acting as a pain receptor agonist [20]. Moreover, the great inhibitory effects of ginger on oxygen free radicals, such as superoxide, hydroxyl radicals, and lipid peroxide, result in its high level of antioxidant activity. Although some studies have reported the effects of ginger on growth factors, it has been shown that synthetic gingerols (the main ingredient of ginger extract), phenyl alkanol analogs, and the aqueous extract of ginger can inhibit platelet serotonin secretion resulting from the accumulation of arachidonic acid in human blood, improve local blood circulation, and, thereby, greatly accelerate the wound healing process [21].
The results of this study indicated that there was no significant difference between the participants treated with ginger extract ointment and placebo ointment in the severity of pain and wound healing status. However, participants in the intervention group took fewer painkillers than those in the control group did.
Although there was no study dealing with the effects of ginger ointment on episiotomy wound healing in humans, many studies have reported the analgesic effects of this plant on dysmenorrhea and other pains in women. Mozaffari et al. studied the effects of rhizome capsules (ginger) on postpartum pain in 128 mothers with moderate to severe pain after vaginal delivery. Participants in Group A (placebo) received 500-mg placebo capsules containing pea flour and those in Group B (intervention) received 500-mg Zintoma capsules (ginger rhizome) every 8 hours from two hours after delivery. In the second and third interventions, Group A and Group B were administered 250-mg placebo capsules and 250-mg Zintoma capsules, respectively. The severity of pain was measured before each intervention and half an hour, one hour, and two hours after each intervention. The mean score of pain significantly reduced in both groups during the interventions, whereas the severity of pain in the intervention group was significantly lower than the control group at any time after the intervention [22]. There are differences between this study and the study conducted by Mozaffari et al.; for example, they treated the participants with an edible ginger medicine and employed a numerical rating scale (NRS) to measure the severity of pain, whereas the participants were treated with ginger ointment and the severity of their pain was measured using VAS in this study.
Ozgoli et al. compared the effects of ginger, mefenamic acid, and ibuprofen on pain in women with primary dysmenorrhea. They selected 150 university students (aged over 18 years) with primary dysmenorrhea from the dormitories of two universities of medical sciences as the sample and alternately assigned them to three groups of equal size. Participants in the ginger group received 250-mg capsules containing rhizome powder four times a day for three days from the beginning of the menstrual cycle, and those in other groups received 250-mg mefenamic acid capsules and 400-mg ibuprofen capsules under the same protocol. The Verbal Multidimensional Scoring System (VMDS) was employed to assess the severity of primary dysmenorrhea. The three groups were also compared in terms of the severity of disease, pain relief, and satisfaction with treatment after a menstrual cycle. The severity of dysmenorrhea significantly reduced in all groups after the treatment, and there was no significant difference between the three groups in the severity of dysmenorrhea, pain relief, and satisfaction with treatment (p > 0.05). They also reported no severe side effects of the treatments [23].
Although they administered ginger to participants orally, they found no significant difference between this method and other methods of administration in terms of effectiveness. However, they also measured dysmenorrhea pain, which is severer than any other postpartum pain.
Kravchenko et al. investigated the analgesic and anti-inflammatory effects of ginger ointment on rats. Inflammation was induced by the sub-plantar injection of 30 µl of allyl isothiocyanate (AITC) solution in 1, 2-propylene glycol into the plantar fascia (aponeurosis) of the hind limb of rats. The dynamics of inflammatory changes was evacuated before and 1, 2, 3, 4, 6, and 24 hours after the injection to measure the volume and thickness of the affected limb. The analgesic effects of ginger ointment were also measured using the AITC-induced pain model. Their results showed that the 0.025% ginger ointment was most effective in inhibiting the inflammatory process and the greatest analgesic effects were observed after using the 0.05% ginger ointment 10 minutes before pain induction [24]. They used a combination of ginger ointment and AITC (an anti-inflammatory solution), whereas the participants in this study were treated only with ginger ointment (containing no anti-inflammatory substance). In addition, Kravchenko et al. studied the pharmacological effects of ginger extract on an AITC-induced model. It can be hence stated that a possible mechanism of this plant is the connection between its compounds to TRPA1 and TRPV1 ion channels.
Kazerouni et al. conducted a review study about the effects of ginger (Zingiber officinale) on skin health status. For this purpose, they selected and reviewed 34 articles on the anti-inflammatory, antioxidant, anti-cancer, and restorative effects of ginger. Since there is currently insufficient evidence that ginger helps heal wounds, inflammation, aging, and cancer, there is a need for stronger evidence to prove the positive effects of this plant on humans. Natural ginger exhibits restorative and antioxidant/anti-inflammatory properties and does not irritate the skin when it is applied to scratches or ulcers. Therefore, it can be used as a topical medicine to improve skin repair [25].
Jamaluddin et al. investigated the effects of ginger extract ointment on the wound healing rate and the wound morphological change in the brown rat (Rattus norvegicus). To this end, they selected 24 brown rats as subjects and assigned them to four groups: two intervention groups (10% and 20% ginger extract ointments), a negative control group (no treatment), and a positive control group (Oxyfresh Soothing Pet Gel®). After making an incision on the back of the subjects, the 14-day treatment (administration of ointments twice a day) began. Their results demonstrated that there was a difference between the negative control group, the positive control group, and intervention groups in terms of the wound surface size. The results also showed that the 10% ginger extract ointment was more effective in accelerating the wound healing process [26]. They tested 10% and 20% ginger ointment on animal subjects, whereas the 0.05% ginger ointment was used for the treatment of participants in this study.
Most studies in this field have focused on animals and a few experimental studies have been conducted on humans. Therefore, there is a need for continuous studies to achieve stronger pieces of evidence proving the effectiveness of ginger in humans. People have shown a greater tendency to use herbal medicines and complementary medicine for the treatment of a variety of diseases in recent years. Ineffectiveness of chemical drugs and unavailability of experienced physicians, on the one hand, and the preparation and availability of complementary therapies and their few side effects and noninvasive nature, on the other hand, are the main reasons why patients are more willing to choose complementary therapy. Studies have shown that complementary medicine is practiced in most countries around the world in different ways such as massage therapy, touch therapy, and aromatherapy. Moreover, 85% of gynecologists and midwives argue that complementary medicine practices can improve the quality of life of people. Although complementary medicine can be used in all fields, it is more commonly and widely employed in oncology, geriatric care, and midwifery for women [27, 28]. This study investigated the therapeutic effects of 0.05% ginger ointment. However, since a few studies have dealt with the therapeutic value of ginger as well as its drug interactions and possible side effects, there is a need for further studies to determine the best form, concentration, and administration time of this plant to achieve the best therapeutic results.
Limitations and strengths
In the present study, how to use the ointment of participants were assumed to be correct as their validation was beyond the researchers’ ability. Among the strengths of this study are observing all principles of clinical trials, including allocation randomization and allocation concealment.