The Effect of St. John's Wort Oil (Hypericum Perforatum L.) in Knee Osteoarthritis: A Randomized Controlled and Qualitative Study

Background

Reducing pain and improving physical function are critical in the treatment of osteoarthritis. Although individuals use St. John's Wort oil to relieve pain due to osteoarthritis, no scientific research has been found investigating its effectiveness.

Aim

This study investigated the effect of St. John's Wort oil on pain intensity and physical functions in people with knee osteoarthritis.

Methods

This study adopted a single-blind, randomized, placebo-controlled, and qualitative mixed design. The sample consisted of 60 patients randomized into intervention (n = 30) and placebo control (n=30) groups. The experimental group participants were treated with topically St. John's Wort oil three times a week for 3 weeks, and the placebo control group participants were treated with olive oil three times a week for 3 weeks. Quantitative data were collected using a patient identification form, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Visual Analogue Scale. Qualitative data were collected through semi-structured interviews.

Results

The experimental group had a significantly lower mean Visual Analog Scale score in the first, third, and fourth follow-ups than the control group. The experimental group had significantly lower mean WOMAC-pain, WOMAC-stiffness, and WOMAC-physical function subscale scores in the last follow-up than in the first follow-up. The qualitative data agreed with the quantitative data.

Conclusions

The results show that St. John's Wort oil helps people with knee osteoarthritis feel less pain and become physically more active. Additional research is warranted to better understand the effect of St. John's Wort oil on pain intensity and physical functions in people with knee osteoarthritis.