The management of burn injury is a long-term process and requires the same priorities as all other trauma patients. Depending on how deeply and severely a burn penetrates the skin’s surface, burn injury is classified as first-, second-, or third-degree. A first-degree burn usually involves only the epidermis with redness, pain, dryness at the burn site with no blisters. A second-degree burn affects the epidermis and dermis, resulting in a red, blistering, swollen, and painful burn site. A third-degree burn damages the epidermis and dermis, leaving the burn site white or charred and devoid of sensation due to the loss of nerve endings [1]. Despite the advances in therapeutic techniques, burn patients of different severities still suffer from considerable pain and discomfort. Burn injuries often include physical, physiological, and sociological consequences which result in poor quality of life [2]. Thus, essential oils which are known to possess therapeutic and medicinal properties have become an option for the management of burns [3].

Aromatherapy, also known as essential oil therapy, uses plant, flower, or herb extracts to enhance health and wellbeing [4,5]. Aromatic essential oils have been widely studied for first-degree burn injuries due to their ability to relieve pain, reduce scarring, as well as reduce inflammation and antimicrobial activity [6]. A review study has shown that aromatherapy could alleviate pain and reduce anxiety by stimulating the parasympathetic nervous system [7]. Moreover, studies have also been shown that essential oils contain chemical constituents with analgesic-like activity and inhalation of essential oils could stimulate the brain to exert neurotransmitters through olfactory system [8,9]. Aromatherapy also contains oxides that have been found to be analgesic [10]. Essential oils could also stimulate endorphin production, resulting in effects such as pain-reducing, stress releasing, relaxed feeling, and alert enhancement [11]. A systematic review also has shown that essential oils contain bioactive constituents with anxiolytic-like activity [12]. A few studies also reported that aromatherapy alleviate symptoms of cancer such as pain and nausea, and symptoms of behavioral and psychological associated with dementia [13,14,15,16,17,18] (Table 1).

2. Aromatherapy for Symptom Relief in Patients with Burn

aromatherapy has the potential in reducing pain and anxiety. Inhaled aromatherapy plus routine care showed beneficial effects in relieving pain after dressing, as compared to placebo plus routine care or routine care alone. Compared to routine care alone, inhaled aromatherapy plus routine care showed superior effects in calming anxiety after dressing. Similarly, aromatherapy massage plus routine care compared with routine care alone also presented favorable effects in easing general anxiety.

First Author (Year) [Ref.]	Total Sample Age (Range or Mean)/ Diagnostic Criteria	Intervention (Regimen)	Control (Regimen)	Main Outcomes	Main Results (Effect Estimate)	Trial Registration Number Registration Time
Bikmoradi (2016) [21]	50 (A: 33, B: 34)/ second degree burn or second and third degree burns	(A) Damask Rose (inhale, 40%, 5 drops, 20 min before dressing, 2 nights, n = 25), plus routine care	(B) Placebo (distilled water, 5–30 min, n = 25), plus routine care	Pain (VAS) [dressing]	MD-0.88 [−1.27, −0.49], p < 0.001	IRCT 201302249759N4 While recruiting
Sadeghi (2020) [22]	120 (A:37, B:37, C:35)/ second degree burns <30%	(A) Damask Rose (inhale, 40%, 6 drops, breath 5 times, 60 min, n = 40), plus C	(B) Placebo (distilled water, 6 drops, breath 5 times, 1 h, n = 40), plus C (C) Routine care (n = 40)	(1) Pain (VAS) (2) Anxiety (STAI) [dressing]	(1) A vs. B, MD-0.82 [−1.25, −0.39], p < 0.001; A vs. C, MD-1.02 [−1.48, −0.56], p < 0.0001 (2) A vs. B, MD-15.85 [−18.35, −13.35], p < 0.00001; A vs. C, MD-3.17 [−3.83,−2.5], p < 0.00001	IRCT 2017030632129N3 While recruiting
Azizi (2019) [23]	120 (A:39, B:37, C:34)/ second degree burns <30%	(A) Lavender (inhale, 2%, 10 drops, breath 5 times, 60 min, 1 time, n = 40), plus C	(B) Placebo (distilled water, 10 drops, 1 h, 1 time, n = 40), plus C (C) Routine care	Pain (VAS) [dressing]	A vs. B, MD-0.38 [−0.94, 0.18], NS; A vs. C, MD-0.40 [−0.88, 0.08], NS	IRCT 2017030632129N3 While recruiting
Daneshpajooh (2019) [24]	140 (A:44, B: 40, C: 41, D: 44)/ second or higher degree burn injury	(A) Rose (inhale, 40%, 5 drops, for 20min, once daily for 3 days, n = 33), plus B	(B) Routine care (n = 33) (C) Benson relaxation (n = 33), plus B (D) A + C (n = 33), plus B	Burn specific pain anxiety scale [dressing]	A vs. B, MD-3.05 [−3.77, −2.33], p < 0.00001	IRCT 20171212037843N1 While recruiting
Harorani (2016) [25]	60 (18–65)/ second degree burns or second and third degree burns together	(A) Lavender (inhale, 2%, 2 drops, 20 min, 3 days, n = 30), plus routine care	(B) Placebo (distilled water, n.r., n = 30), plus routine care	Anxiety (STAI) [general]	MD-4.60 [-7.07, -2.13], p < 0.001	IRCT 2013042413110N1 While recruiting
Seyyed-Rasooli (2016) [26]	90 (A: 35, B: 35, C: 38)/ second degree burns <20%/	(A) Essential oils (inhale, lavender oil 7 drops and Rosa damascene 3 drops, 30min, n.r., n = 30), plus C (B) Essential oils (massage, lavender oil 7 drops and Rosa damascene 3 drops, 30 min, n.r., n = 30), plus C	(C) Routine care (n = 30)	(1) Pain (VAS) (2) Anxiety (STAI) [general]	(1) A vs. C: MD-1.73 [−3.03, −0.43], p < 0.05; B vs. C: −2.46 [−3.64, −1.28], p < 0.0001; A vs. B: 0.73 [−0.54, 2.00], NS (2) A vs. C: MD-4.76 [−9.93, 0.41], NS; B vs. C: MD-3.03 [−8.36, 2.30], NS; A vs. B: −1.73 [−7.21, 3.75], NS	IRCT 201404176918N17 While recruiting
Rafii (2020) [27]	105 (A: 36, B: 37, C: 40)/ second- and third-degree burns	(A) Aroma (massage, lavender oil 2 drops and chamomile 2 drops, 20 min, 3 session within 1 week, n = 35), plus C	(B) Placebo (massage, bady oil, 20 min, 3 session within 1 week, n = 35), plus C (C) Routine care (n = 35)	(1) Anxiety (STAI) (2) Sleep [general]	(1) A vs. B: MD-0.82 [−3.30, 1.66], NS; A vs. C: MD-5.26 [−7.72, −2.80], p < 0.0001 (2) A vs. B: MD-1.58 [−2.92, −0.24], p < 0.05; A vs. C: MD-1.83 [−3.30, −0.36], p = 0.01	IRCT 20180120038444N1 Prospective
van Dijk (2018) [28]	287 children (A: 24, B: 28, C: 25 months)/ second- and third-degree burns Burn incident <1 week	(A) Aroma (massage, 1% essential oils (chamomile, lavender, neroli), 10–20 min, 1–5 session within 2 weeks, n = 108), plus C	(B) Placebo (massage, carrier oil, 10–20 min, 5 session within 2 weeks, n = 90), plus C (C) Standard nursing care (n = 86)	(1) MTI, BSC (2) COMFORT-B (3) Distress (NRS) [general]	(1) NA † (2) NS (3) NS	Trial NL3771 (NTR3929) Prospective

The management of burn patients requires delicate care especially in the aspect of pain and anxiety. Aromatherapy has shown encouraging effects in easing pain and anxiety and could play a role in complementing daily routine care. In the meantime, more studies are needed to guide the recommendation of aromatherapy in clinical practice. Current available studies are insufficient to demonstrate great significant effects of aromatherapy in managing burn. As management of burn is often long-termed, it is necessary to extend the period of aromatherapy intervention to fully evaluate its effectiveness. Besides, future studies should also consider a single type of essential oil as the smell and function of each type of essential oil are distinct. In general, well-designed RCT with proper reporting, longer intervention period with specific essential oil, and larger sample size are needed to validate the usage and effectiveness of aromatherapy for the management of burn.