Pre-procedural information form, state-trait anxiety scale, and comfort scale were applied to patients who had planned colonoscopy.

Two drops of lavender (2%) essential oil was dripped onto a 2 x 2 cm cotton gauze cloth attached to the front of the clothes of the experimental group patients, approximately 12 inches below their noses.

They were asked to inhale 2% lavender essential oil for 20 minutes. They were directed to breathe normally after inhalation.

Vital signs of the patients were checked before and after the procedure. After the process, the forms were filled again, the final test process was completed.

Pre-procedural information form, state-trait anxiety scale, and comfort scale were applied to patients who had planned colonoscopy. Lavender aromatherapy was not applied to the patients in this group, but routine care was applied.

After the process, the forms were filled again, the final test process was completed. The data took about 15-20 minutes with face-to-face interview method.

Two drops of lavender (2%) essential oil were dripped onto a 2 x 2 cm cotton gauze cloth attached to the front of the clothes of the experimental group patients, approximately 12 inches below their noses. They were asked to inhale 2% lavender essential oil for 20 minutes. They were directed to breathe normally after inhalation. Vital signs of the patients were checked before and after the procedure. After the process, the forms were filled again, the final test process was completed.

State anxiety inventory determines how an individual feels at a certain moment and under certain conditions. The trait anxiety inventory, on the other hand, is defined as the anxiety that an individual feels in his normal life. Each item in the inventory is evaluated between one and four points. High total scores in the inventories indicate a high state anxiety level of the individual. In the inventory, scores above 42 are considered as "high anxiety level". The internal consistency (Cronbach's Alpha) coefficients of this inventory range from 0.83 to 0.92 for the state anxiety inventory.

The State-Trait Anxiety inventory was evaluated 20 minutes before and 20 minutes after colonoscopy in the intervention and control groups. Anxiety level was evaluated with the State-Trait Anxiety inventory before and 20 minutes after lavender oil inhalation in patients in the intervention group.

General Comfort Scale: The scale consists of 28 questions and shows the current comfort status of the patient. The score of the scale varies between 28-168. The Cronbach alpha of the 6-point Likert-type scale is 0.82.

The general comfort scale was evaluated 20 minutes before and 20 minutes after colonoscopy in the intervention and control groups. Overall comfort level was assessed before and 20 minutes after lavender oil inhalation in patients in the intervention group. A high score on the scale indicates that the general comfort level of the patients is high.