Written by Tabish Mehraj, PhD. This study found that thyme oil significantly improved symptoms, including shortness of breath, dizziness, diarrhea, weakness, loss of appetite, cough, headache, and muscle/joint pain. It also significantly reduced body temperature, pulse rate, and respiratory rate, increased SpO₂, and improved blood gas parameters by decreasing CO₂ and increasing O₂ (all p<0.05), while blood pressure remained unchanged (p > 0.05).

The symptoms of COVID-19 infection typically involve the lower respiratory tract and appear after the incubation period. The symptoms and severity of the disease depend on various factors, such as a person’s age, immune system, and history of chronic disease. Fever, cough, fatigue, myalgia, diarrhea, and headache are the most common symptoms. Several supportive therapies are available to help alleviate symptoms associated with COVID-19. Thymus vulgaris (thyme) is an herb that is rich in compounds such as carvacrol and thymol and has been used to treat respiratory ailments because of its antimicrobial, anti-inflammatory, antioxidant, and bronchodilatory properties.

This study, conducted by Öner and Cengiz, assessed whether inhaled thyme essential oil could improve COVID-19 symptoms and hemodynamic parameters in hospitalized patients receiving standard medical care. The study enrolled 140 patients with PCR-confirmed COVID-19 and moderate lung involvement (50–80% on computed tomography). Participants were randomly assigned to the intervention group (n = 70) and the control group (n = 70). All patients received the same standard COVID-19 treatment; however, the intervention group inhaled thyme essential oil via inhaler stick in addition for 5 consecutive days. Symptoms and vital signs, such as blood gas parameters and oxygen saturation, were recorded before treatment and monitored throughout the five-day intervention.

Results/ Key Findings

• Thyme oil significantly improved symptoms, including shortness of breath, cough, weakness, headache, muscle/joint pain, diarrhea, and loss of appetite in COVID-19 patients.
• It reduced pulse rate, and respiratory rate, while increasing oxygen saturation (SpO₂) and improving blood gas parameters (p < 0.05).
• Improvements in nausea, vomiting, runny nose, and loss of taste or smell were observed but were not statistically significant.
• Thyme’s anti-inflammatory, antioxidant, and antimicrobial properties may contribute to symptom relief.
• Current evidence suggests thyme may be a useful adjunct to standard care, but larger clinical trials are needed to confirm its efficacy.

Several strengths enhance confidence in these findings. The study employed a randomized controlled design with an adequately powered sample size and balanced treatment groups through block randomization based on age and sex. All participants received identical standard medical therapy, allowing the additional effects of thyme aromatherapy to be evaluated more accurately. Repeated measurements of symptoms, vital signs, and blood gas parameters over five days provided a comprehensive assessment of treatment response. Furthermore, this is one of the first clinical trials to simultaneously evaluate COVID-19 symptoms, vital signs, and hemodynamic outcomes following thyme oil aromatherapy delivered via a portable inhaler.

Despite these strengths, the study has important limitations. The baseline control group had statistically more chronic disease and COPD. The fact that the control group had at baseline a significant greater risk of complication introduces a major confounding factor. Participants and investigators were not blinded because the intervention involved a recognizable aroma, which introduced the potential for expectancy and observer bias, particularly in subjective symptom assessments. The inhalation technique could not be perfectly standardized across participants, potentially resulting in variability in the delivered dose. Although all patients received the same standard COVID-19 treatment protocol, the investigators did not comprehensively document any additional medications individual patients may have received, which could have influenced outcomes. The intervention lasted only five days, preventing assessment of long-term recovery or persistent symptoms. Finally, because the study included only hospitalized patients with moderate COVID-19, the findings may not be generalizable to patients with mild disease, those with severe illness requiring intensive care, or patients with other respiratory infections.

Overall, this randomized controlled trial suggests that inhaled thyme essential oil may serve as a safe, inexpensive adjunct to standard medical treatment for hospitalized COVID-19 patients. The intervention improved multiple respiratory symptoms, enhanced oxygenation, and favorably influenced several physiological parameters without replacing conventional therapy. Larger, blinded clinical trials with longer follow-up period are needed to confirm these findings and determine whether thyme aromatherapy can improve long-term clinical outcomes in respiratory diseases.

Click here to read the full text study.

Posted July 16, 2026.

Dr. Tabish Mehraj is a pharmaceutical scientist with expertise in pharmaceutics, drug delivery, and formulation development. She earned her PhD in Pharmaceutical Sciences from the University of Mississippi, where her research focused on the formulation, optimization, and characterization of lipid-based nanocarriers for targeted liver delivery of antimalarial therapeutics. Dr. Mehraj has also served as an ORISE Fellow at the U.S. Food and Drug Administration (FDA), where she evaluated the effects of formulation and process design on the quality and performance of intravaginal drug delivery systems and developed bio-relevant in vitro drug release testing methods. She has teaching experience in pharmaceutical and life sciences courses and has authored peer-reviewed publications, book chapters, and conference presentations. Dr. Mehraj is an active member of the American Association of Pharmaceutical Scientists and has been recognized by honor societies including Rho Chi and Gamma Beta Phi.

Reference:

1. Öner, U., & Cengiz, Z. (2024). The effects of aromatherapy with thyme oil on disease symptoms, vital findings, and hemodynamic parameters in COVID-19 patients. Explore, 20(4), 544-553.