Objective
Coronavirus disease 2019 (COVID-19) has spread worldwide, and several virus variants have emerged. Vaccines are administered to help prevent the infection. In Republic of Korea, most people take herbal medicine. This study investigated the use of herbal medicine to counter the side effects of COVID-19 vaccines.

Methods
This cross-sectional study was conducted using an online survey. Chi-square tests were used to determine differences in the use of herbal medication according to sociodemographic characteristics. Independent two-sample and paired t-tests were performed to examine the effect and satisfaction of herbal medicine use for countering the side effects of COVID-19 vaccines. One-way analysis of variance was used to determine vaccine-related differences.

Results
A total of 233 and 181 participants received the first and second doses of COVID-19 vaccines, respectively. The majority of herbal medicine users were in their thirties, had a bachelor’s degree, suffered from side effects of vaccination, and received Vaxzevria for their first COVID-19 vaccine dose and Comirnaty for their second dose. The herbal medicine group had a higher satisfaction level of post-vaccination side effects than the non-herbal medicine group (P < 0.0001). The numeric rating scale scores for vaccination side effects were lower among participants who took herbal medication to alleviate those symptoms (P < 0.0001). The most commonly used herbal formula was Shuanghetang.

Conclusion
A third of participants receiving COVID-19 vaccines used herbal medication to counter the side effects of vaccination. The use of herbal medicine was associated with age, education level, vaccine brand, and whether side effects of vaccination occurred. Herbal medication use was associated with greater satisfaction compared to vaccine recipients not using herbal medication.

Key words: COVID-19 vaccines, Herbal medicine, Side effects, Republic of Korea