Introduction
Hernia refers to the protrusion of an organ or tissue through a weakened area in which the organ is enclosed. This disease can occur at any age and gender. The most common type of hernia is indirect inguinal hernias, which mainly seen in men. In the last two decades, there have been developments in the control of postoperative pain intensity. Postoperative pain, if not controlled, can cause a range of acute and chronic effects. If pain is controlled during and after surgery, by interfering with the pathophysiological changes that occur during surgery, the subsequent complications can be reduced. It shortens the recovery period after surgery and after discharge from the hospital. The lettuce family consists of about 100 species. Many sources of Iranian traditional medicine and folk medicine indicate the analgesic properties of lettuce. This study aims to investigate the effectiveness of oral lettuce syrup consumption as an adjunctive treatment in reducing pain after inguinal hernia surgery.
Materials and Methods
 This is a triple-blind clinical trial. Seventy candidates for inguinal hernia surgery referred to Valiasr Hospital in Arak, Iran were included in the study after signing the informed consent form. Before entering the operating room, the patients did not receive any special medication. All patients were operated by one surgeon. Patients were randomly divided into two groups by the ward nurse using a random numbers table. One group received 0.1 ml/kg lettuce syrup three times a day (every 8 hours) three days before surgery, and the other group received a placebo with the same shape, color and taste in uniform glass bottles provided by the same drug company. The bottles were labeled A and B by the pharmaceutical company. Lettuce syrup and placebo consumption were stopped 8 hours before the operation. After the operation, they received another dose of them immediately after the start of feeding. The amount of pain was measured using the visual analogue scale (VAS) during recovery and 1, 2, 4, 6, 12, and 24 hours after the operation by the resident. If VAS score was more than 3 at any time after the surgery, the patients would be given 0.5-1 mg/kg of morphine (depending on the pain intensity) and the total amount of the prescribed drug and the time of drug reception were recorded. The data were entered in SPSS v.24 software. Then, the normality of data distribution was checked to determine the use of parametric or non-parametric tests. Chi-square test, t-test, and repeated measures analysis of variance were used. P<0.05 was statistically significant.
Results 
In all time points, the intensity of pain was significantly (P<0.001) higher in the placebo group than in the intervention group treated with lettuce syrup. One hour after the operation, patients had a VAS score of 2.41±0.86 in the intervention group and 3.22±1.17 in the placebo group. Two hours after the surgery, the mean VAS score was 2.84±0.94 in the intervention group and 3.72±1.28 in the placebo group. No significant difference was observed in the results between hours 1 and 2 after the surgery. Four hours after surgery, the mean VAS score was 1.34±3.63 in the intervention group and 4.58±1.57 in the placebo group. Six hours after surgery, the mean VAS score was 4.83±1.55 in the intervention group and 6.11±2.03 in the placebo group. Twelve hours after the surgery, the mean VAS score was 1.61±0.59 in the intervention group and 7.01±2.19 in the placebo group. The results showed a significant increase in the amount of pain from 2 to 12 hours after surgery. Twenty-four hours after surgery, the mean VAS score was 1.94±0.68 in the intervention group and 8.13±2.75 in the placebo group, which significantly decreased compared to the previous time points. This indicates that the best time for the analgesic effect of lettuce syrup is 24 hours after surgery. In the placebo group, we observed an increase in the amount of pain at different time points. The results of repeated measure analysis of variance confirmed that lettuce syrup consumption was effective in reducing post-surgery pain over different times.

Ethical Considerations
Compliance with ethical guidelines
All ethical principles are considered in this article. The participants were informed of the purpose of the research and its implementation stages. They were also assured about the confidentiality of their information and were free to leave the study whenever they wished, and if desired, the research results would be available to them.

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 

Authors' contributions
Conceptualization, methodology, investigation and writing –‌original draft: All authors; Writing–review & editing, funding acquisition, resources, supervision: Seied Amirhosein Latifi.

Conflicts of interest
The authors declared no conflict of interest.


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