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Iranian Red Crescent Medical Journal
Study of the Effect of Mint Oil on Nausea and Vomiting During Pregnancy
Hajar Pasha
1
, Fereshteh Behmanesh
2*
, Farideh Mohsenzadeh
2
, Mahmood Hajahmadi
3
, Ali
Akbar Moghadamnia
4
1
Fatemeh Zahra Fertility and Infertility Health Research Center, Babol University of Medical Sciences, Babol, Iran
2
Department of Midwifery, Babol University of Medical Sciences, Babol, Iran
3
Department of Community Medicine, Babol University of Medical Sciences, Babol, Iran
4
Department of Pharmacology, Babol University of Medical Sciences, Babol, Iran
* Corresponding author: Fereshteh Behmanesh, Department of Midwifery, Babol University of Medical Science, Babol, Iran. Tel.: +98-1112199592, Fax: +98-
1112199936, E-mail: f24farzan45@gmail.com
ABSTRACT
Background: Approximately 80 percent of pregnant women suffer by some degree of nausea and vomiting. But the treatment of nausea and
vomiting of pregnancy is rarely successful.
Objectives: The aim of this study was evaluation the effect of mint on nausea and vomiting during pregnancy that its treatment in some
recent research has been effective.
Materials and Methods: In this double blind RCT, 60 pregnant women with nausea and vomiting of pregnancy were sampled and divided
into two groups with Block-randomized method. mint group, in addition to giving the routine training, for four consecutive nights, before
sleeping, a bowel of water whit four drops of pure mint essential oil placed on the floor near their beds and in control groups were used four
drops of normal saline . The severity of nausea by using Visual Analog Scale (VAS) and severity of vomiting by counting the number of its in 7
days prior, 4 days during, and 7 days after intervention were assessed.
Results: The results showed that the severity of nausea and vomiting did not differ between the two groups in 7days before and after
intervention by using repeated measurement test. But during intervention, the severity of nausea showed a decreasing trend (especially
in 4th night) in the mint and an increasing trend in the control group. The severity of nausea within 7 days after the intervention had a
decreasing trend in both groups; however, the intensity was lower in the mint than saline group but not statically significant. No meaningful
relationship has been detected during and after intervention for the intensity of vomiting.
Conclusions: The results of study showed that peppermint essential oil hasn't the effect on nausea and vomiting of pregnancy.
Keywords: Mentha piperita; Nausea; Vomiting; Aromatherapy
Article type: Research Article; Received: 09 Nov 2011, Revised: 03 Apr 2012, Accepted: 17 Apr 2012; DOI: 10.5812/ircmj.3477
Implication for health policy/practice/research/medical education:
This study is going to evaluate the effect of mint on nausea and vomiting during pregnancy.
Please cite this paper as:
Pasha H, Behmanesh F, Mohsenzadeh F, Hajahmadi M, Moghadamnia AA. Study of the Effect of Mint Oil on Nausea and Vomiting
During Pregnancy. Iran Red Cres Med J.2012;14(11):744-7. DOI: 10.5812/ircmj.3477
Copyright © 2012, Iranian Red Crescent Medical Journal; Published by Kowsar Corp.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which per-
mits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Background
Nausea and vomiting are among the common prob-
lems in the first half of pregnancy (1). Approximately
%80 percent of women are influenced during pregnancy,
along with significant impact on their quality of life (2,3).
The reason behind gestational nausea and vomiting is
not still well defined (1). In spite of temporal relationship,
there is no constant correlation between the severity of
nausea and vomiting and increased level of chorionic go-
nadotropin; however, since conditions with high HCG lev-
el, such as molar and multiple pregnancies, are accompa-
nied by higher rates of nausea and vomiting, (4) it seems
that nausea is probably caused by increment in estrogen
parallel to increase in gonadotropin level (1). Treatment
of gestational nausea and vomiting is rarely so successful
that the pregnant women could reach to a full recovery.
The problem is somehow alleviated by measures such as
trying to eat less in more servings, stop eating before sa-
tiety, and Nonetheless, vomiting is sometimes so severe
that does not respond to treatments; in these cases, drugs
such as vitamin B6 (5,6), promethazine, and are used (1).
These drugs are associated with side effects (7). In a study
Effect of Mint Oil on Vomiting During Pregnancy
Pasha H et al.
745
Iran Red Crescent Med J. 2012:14(11)
showed that 34% of women did not use drug treatment
(vitamin B6), and 26% administered it less than the pre-
scribed dose, and ascribed it to lack of trust in drug safety
during pregnancy and the preference to non-medical
approach (2). Application of complementary and alter-
native medicine is the major trend recently occurred in
medical care that can even reduce plasma level of stress
hormones (8). Although healing ingredients of essential
oils are broadly used in medicine throughout the world
(9), administration of herbal medicines is limited during
pregnancy due to unawareness of their mechanisms of
action and lack of randomized controlled trials in this
field. Yet, the study showed that 85% of midwives recom-
mend herbal remedies, regardless of their side effects,
to pregnant women for treating gestational nausea and
vomiting (10). Among the herbal medicines mentioned
in recent researches to treat nausea and vomiting of
pregnancy, mint can be enumerated (11,12).
2. Objectives
The present study has been carried out to evaluate the
effect of mint oil on nausea and vomiting during preg-
nancy.
3. Materials and Methods
This double blind clinical trial was conducted, after get-
ting approval by Ethics Committee of Babol University
of Medical Sciences and permission for research imple-
mentation, on 60 pregnant women complaining of ges-
tational nausea and vomiting sampled by the researcher
from prenatal ward of seven selected health clinics based
on inclusion (14-35 years, singleton gestation, first tri-
mester pregnancy) and exclusion criteria; well-known
underlying physical or psychological problems, dead em-
bryo or fetus with diagnosed malformation, severe ges-
tational nausea and vomiting, multiple gestations and
hydatiform mole, and those applied other medication
for nausea and vomiting were excluded from this study.
Women intended to participate were given the informed
consent and were randomly allocated to mint oil (n = 30)
and normal saline (n = 30) groups ( Figure 1 ). In addition
to receiving the routine training on diminishing gesta-
tional nausea, such as more meals and less food per meal,
refraining from eating before reaching satiety, avoiding
fatty and spicy foods, eating crackers or dry bread before
getting up from sleep and keeping hydration (10), the
mint group samples were assigned to use a bowl of wa-
ter with 4 drops of pure mint oil (purchased from Kashan
Barij Essence Company) placed on the floor near their
beds for four consecutive nights before sleeping to lessen
the morning sickness (13,14). Despite the same instruc-
tion to the other group, the placebo samples were given
a container with normal saline to use it according to the
mentioned approach. It should be noted that both drug
and placebo were pre-coded by the consultant pharma-
cist and were unknown to the researcher and the mother.
Some mint oil was poured to inner parts of drug's lid,
so that mothers receiving the normal saline cannot be
aware of being allocated to this group. The visual analog
scale was used to assess the severity of nausea. This objec-
tive instrument includes a 10 cm line with areas with a
definite beginning and the end and a specified range, on
which patients determine their health status. Scores zero
and ten are respectively indicative of the best and the
worst condition. Nausea intensity-recording visual scale
is a self-reporting measure, and since nausea is a sensa-
tion felt by patient, it is a highly appropriate technique
for measuring the related intensity; in addition, percep-
tion and education of recording manner is easy for the
study samples (15). To evaluate the severity of vomiting,
the frequency of vomiting and retching was counted.
Variables such as maternal age, gestational age, educa-
tion, occupation, place of residence, and BMI were also
assessed in terms of group matching. After getting the
information, the data were analyzed through descrip-
tive-analytical statistic by SPSS software. Demographic
characteristics (i.e., Age, BMI, Gestational age educational
level, Occupation, Place of residence) were summarized
to characterize the study population. Statistical analyses
were performed using t-test (i.e., mean of age, gestational
age, BMI), Chi Square (i.e., educational level, Occupation,
Place of residence), and repeated measurement (i.e., the
severity of nausea before, during, and after intervention
in the study groups, the severity of vomiting before, dur-
ing, and after intervention in the study groups) to deter-
mine potentially significant associations, and a p value
less than 0.05 was considered significant.
4. Results
The results showed similarity between the two groups
regarding the maternal age, gestational age, education,
occupation, place of residence, and BMI. The minimum
and the maximum ages were respectively 14 and 34 years
old, 45% of participants were in the age range of 20-25
years. Most of the samples (25%) were in their 8 weeks of
gestation ( Table 1 ).
Results showed similar intensity of nausea and vomit-
ing from 7 days before the intervention. The mean of nau-
sea and vomiting intensity was 4.78 ± 1.62, 4.85 ± 1.82 and
3.00 ± 2.19, 2.52 ± 2.4 in mint and saline groups (P value =
0.865, 0.389).
In the first to fourth days of intervention, the severity
of nausea showed a decreasing trend (especially in the
fourth night) in the mint and an increasing tendency in
the control group ( Figure 2 ).The mean of nausea inten-
sity in mint and saline groups was 3.50 ± 1.95, 4.38 ± 2.18
(P value = 0.140).The mean of vomiting intensity within 4
days the intervention in mint and saline groups was 2.23
± 1.88, 2.55 ± 2.55 (P value = 0.577).
Effect of Mint Oil on Vomiting During Pregnancy
Pasha H et al.
Iran Red Crescent Med J. 2012:14(11)746
150 were invited to participate in the study
Women Randomized into trial
(n=67)
Assigned to intervention
(n=33)
Assigned to control
(
n=34
)
Completed follow-up
(n=30)
Lost to follow-up
(n=3)
1 participate due to
intolerance to the
mint oil
1participiate for
using of other drugs
1 participate for not
returning the
q
uestionnaire
83 excluded:
50 women refused
to participate;
because of they
intended to begin
another treatment.
- 10 women
refused to
participate
-3 women were
multiple
pregnancies
-10 women were
the second
trimester
-2 sever
gestational nausea
and vomiting
8 were high risk
Completed follow-up
(n=30)
Lost to follow-up
(n=4)
2 participate for using
of other drugs
2 participate for not
returning the
questionnaire
Figure 1. Flow Diagram of Participants Through each Stage of Random-
ized, Controlled Trial
Table 1. Comparison of demographic characteristics between
two groups of mint oil and normal saline
Mint oil Normal
saline
P value
Age, Mean ± SD 24.8 ± 3.56 25.1 ± 4.76 0.783
BMI, Mean
± SD
24.84 ± 2.99 25.54 ± 3.81 0.434
Gestational
age, Mean ± SD
9.07 ± 1.31 9.73 ± 2.21 0.161
Education, No
(%)
0.530
< High school 9 (30) 10 (33.3)
High school 18 (60) 14 (46.7)
University 30 (10) 6 (20)
Occupation,
No (%)
0.646
Housekeeper 26 (86.7) 26 (86.7)
Employed 4 (13.3) 4 (13.3)
Place of resi-
dence, No (%)
0.602
Rental 15 (50) 15 (50)
Personal 15 (50) 15 (50)
4.233
4.367
4.267
4.333
3.833
3.733
3.367
3.067
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
1 day2 day3 day 4 day
Means of nausea
Date of intervention
Normal Sali
ne
Mint
Figure 2. The severity of nausea during the 4 days of intervention in nor-
mal saline and mint groups (4.30 ± 2.39, 3.59 ± 2.52)
It has also been observed that within 7 days after the
intervention, severity of nausea had a decreasing trend
in both groups; however, the intensity was lower in the
mint than the control but not statistically significant .No
meaningful relationship has been detected seven days af-
ter the intervention for the intensity of vomiting.
5. Discussion
According to findings of the present study, mint oil aro-
matherapy has not been effective in reducing gestational
nausea and vomiting; although it led to decline in nau-
sea intensity during the intervention in the mint group
(especially on the fourth night) and after intervention in
both groups (more in the mint group), the difference was
not statistically meaningful, that it could be probably
due to the small sample size used in the study.
Different results have been brought about by studies
conducted on the effect of mint on nausea and vomit-
ing. Some studies have suggested that aromatherapy
can relieve nausea or vomiting in the first trimester of
pregnancy and also during the labor (9,16,17). Researches
indicate an increasing percentage of mint administra-
tion and support it for relieving nausea and vomiting
during pregnancy; in other studies, mint has been used
to reduce the morning sickness during pregnancy in 41%
of cases (18). However, owing to the use of other medica-
tions by patients for symptoms alleviation, no precise
scientific connection was found between aromatherapy
and nausea abatement (11,19).
Other investigations have presented ineffectiveness
of peppermint on gestational nausea and vomiting.In
the same study showed that although ginger, mint and
cannabis have been beneficial to treat nausea and vom-
iting caused by other conditions such as chemotherapy
and surgery but only ginger was as the anti-nausea
drug in pregnancy (20). Similar to the present study,
mint has been ineffective on nausea and vomiting dur-
Effect of Mint Oil on Vomiting During Pregnancy
Pasha H et al.
747
Iran Red Crescent Med J. 2012:14(11)
ing pregnancy in this research. Likewise, Anderson and
colleagues (2004) has reported that peppermint oil has
been effectively useful to reduce the severity of nausea
after the surgery, in which mint was compared with iso-
propyl alcohol and placebo (saline), positive effects of
aromatherapy have been suggested to be mainly associ-
ated to the controlled breathing than the aromatherapy
itself since reducing effect of saline was similar to that of
peppermint and alcohol (21).
On the other hand, Noureddini (2005) demonstrated
that oral use of peppermint essential oil contributes to
reversible reduction in gastric acid secretion in rats and,
therefore, recommended it to patients with gastrointesti-
nal problems (22). The reason behind such a controversy
between the mentioned survey and the present research
may be for types of the study samples used. Due to differ-
ences in the mechanisms existing in human and animals
and, more importantly, dependence of nausea on psy-
chological factors and individual condition, the same
results cannot be observed in animal studies and human
researches. Among the many limitation of the study, par-
ticipants' different responses to mint oil aromatherapy
can be enumerated as it was very pleasant to some and
disgusting to others. Basically, in aromatherapy, each
patient needs to smell a particular odor based on his/
her own social and psychological conditions and reacts
to a specific aroma. Not measuring the hormones level
plausibly affecting the gestational nausea and vomiting,
such as estrogen, progesterone and HCG, was another
constraint of the study; albeit, the probable effect of this
limitation was tried to be declined through the measure-
ment of nausea and vomiting 7 days prior to the interven-
tion. Considering the decreasing trend of the intensity of
nausea during the intervention, and lower rates of nau-
sea 7 days after the intervention in the mint group, more
precise findings can be achieved by further investiga-
tions and larger sample size.
Acknowledgements
The authors would like to appreciate Research Deputy
of Babol University of Medical Sciences for financially
supporting the project, and all who sincerely cooperated
in the study.
Funding/Support
None declared.
Financial Disclosure
None declared.
References
1. Cunningham FG, Leveno KJ, Bloom SL, Hauth JC, Rouse DJ, Spong
CY. Prenatal Care. In: Cunningham FG, Leveno KJ, Bloom SL,
Hauth JC, Gilstrap LC, Wenstrom KD, editors. Williams Obstetrics:
23rd Edition: McGraw-Hill; 2010.
2. Baggley A, Navioz Y, Maltepe C, Koren G, Einarson A. Determi-
nants of women's decision making on whether to treat nausea
and vomiting of pregnancy pharmacologically J Midwifery Wom-
ens Health. 2004;49(9):350-4.
3. O'Brien B, Naber S. Nausea and vomiting during pregnancy: ef-
fects on the quality of women's lives Birth. 1992;19(3):138-43.
4. Dadleszen PV. The Etiology of Nausea and Vomiting of Pregnancy.
2004 [updated 2004; cited 2011]; Available from: http://www.nvp-
volumes.org/p1_1.htm.
5. Ben-Aroya Z, Lurie S, Segal D, Hallak M, Glezerman M. Association
of nausea and vomiting in pregnancy with lower body mass in-
dex Eur J Obstet Gynecol Reprod Biol. 2005;118(2):196-8.
6. Sahakian V, Rouse D, Sipes S, Rose N, Niebyl J. Vitamin B6 is effec-
tive therapy for nausea and vomiting of pregnancy: a random-
ized, double-blind placebo-controlled study Obstet Gynecol.
1991;78(1):33-6.
7. Gasiani SS. Iran Pharma-A comprehensive Test Book of Drug informa-
tion. Tehran: Teimorzadeh; 2008..
8. Trease GE, Evans WC. Pharmacognosy. London: Sunders; 2000.
9. Francoise R. Aromatherapy for Labor and Childbirth. 2012 [up-
dated 2012; cited 2011]; Available from: http://www.selfgrowth.
com/articles/Rapp26.html.
10. Wills G, Forster D. Nausea and vomiting in pregnancy: what ad-
vice do midwives give? Midwifery. 2008;24(4):390-8.
11. Gilligan N. The palliation of nausea in hospice and palliative
care patients with essential oils of Pimpinella anisum (aniseed),
Foeniculum vulgare var. dulce (sweet fennel), Anthemis nobilis
(Roman chamomile) and Mentha x piperita (peppermint) Inte J
Aromatherapy. 2005;15(4):163-7.
12. Wilkinson JM. What do we know about herbal morning sickness
treatments? A literature survey Midwifery. 2000;16(3):224-8.
13. Wong C. Natural Morning Sickness Remedies. 2007 [updated
2007; cited 2011]; Available from: www.altmedicine.about.com.
14. Karen B. Pregnancy, Labour, Life and Aromatherapy. 2004 [up-
dated 2004; cited 2011]; Available from: http://www.aroma-
healthtips.co.uk/article/pregnant01.htm.
15. Fazel N. [The effect of mint essence on gastrointestinal disorder
after cesarean section] in Persian Iran J Nurs. 2004;17(38):8-15.
16. Burns EE, Blamey C, Ersser SJ, Barnetson L, Lloyd AJ. An investi-
gation into the use of aromatherapy in intrapartum midwifery
practice J Altern Complement Med. 2000;6(2):141-7.
17. Pasha H, Ghazinejad N, Hosseinzade A. Evaluation of Aroma-
therapy on delivery process J Gorgan Bouyeh Fac Nurs Midwife.
2009;6(15):62-8.
18. Yeh HY, Chen YC, Chen FP, Chou LF, Chen TJ, Hwang SJ. Use of tra-
ditional Chinese medicine among pregnant women in Taiwan
Int J Gynaecol Obstet. 2009;107(2):147-50.
19. Burns E, Blamey C, Ersser SJ, Lloyd AJ, Barnetson L. The use of aro-
matherapy in intrapartum midwifery practice an observational
study Complement Ther Nurs Midwifery. 2000;6(1):33-4.
20. Westfall RE. Use of anti-emetic herbs in pregnancy: women's
choices, and the question of safety and efficacy Complement Ther
Nurs Midwifery. 2004;10(1):30-6.
21. Anderson LA, Gross JB. Aromatherapy with peppermint, isopro-
pyl alcohol, or placebo is equally effective in relieving postopera-
tive nausea J Perianesth Nurs. 2004;19(1):29-35.
22. Noureddini M. Evaluation of the effects of intragastric pepper-
mint essential oil on the secretion of gastric acid in male rat Feyz
J Kashan Univ Med Scie. 2005;8(4).