Symptoms in the Pharmacy :Gastrointestinal Tract Problems(10)

Motion sickness and its prevention

Motion sickness is thought to be caused by a conflict of messages to

the brain, where the vomiting centre receives information from the
eyes, the GI tract and the vestibular system in the ear. Symptoms of
motion sickness include nausea and sometimes vomiting, pallor and
cold sweats.

Parents commonly seek advice about how to prevent

motion sickness in children, in whom the problem is most common.
Any form of travel can produce symptoms, including air, sea and road.
Effective prophylactic treatments are available OTC and can be
selected to match the patient’s needs.

What  you  need to know

• Age
• Infant, child, adult
• Previous history
• Mode of travel: car, bus, air, ferry, etc.
• Length of journey
• Medication

Significance of questions and answers
Age
Motion sickness is common in young children. Babies and very young
children up to 2 years of age seem to only rarely suffer from the
problem and therefore do not usually require treatment. The incidence
of motion sickness seems to greatly reduce with age, although some
adults still experience symptoms. The minimum age at which products
designed to prevent motion sickness can be given varies, so for a
family with several children careful product selection can provide
one medicine to treat all cases. 

Previous history
The pharmacist should ascertain which members of the family have
previously experienced motion sickness and for whom treatment will
be needed.

Mode of travel/length of journey
Details of the journey to be undertaken are useful. The estimated
length of time to be spent travelling will help the pharmacist in the
selection of prophylactic treatment, since the length of action of
available drugs varies.
Once vomiting starts there is little that can be done, so any medicine
recommended by the pharmacist must be taken in good time before
the journey if it is to be effective. The fact that it is important that the
symptoms are prevented before they can gain a hold should be emphasised
to the parents. If it is a long journey, it may be necessary to
repeat the dose while travelling and the recommended dosage interval
should be stressed.

The pharmacist can also offer useful general advice about reducing
motion sickness according to the method of transport to be used. For
example, children are less likely to feel or be sick if they can see out of
the car, so appropriate seats can be used to elevate the seating position
of small children. This seems to be effective in practice and is thought
to be because it allows the child to see relatively still objects outside
the car. This ability to focus on such objects may help to settle the
brain’s receipt of conflicting messages.

For any method of travel, children are less likely to experience
symptoms if they are kept occupied by playing games as they are
therefore concentrating on something else. However, again, it seems
that looking outside at still objects remains helpful and that a simple
game, e.g. ‘I Spy’, is better than reading in this respect. In fact, for
many travel sickness sufferers, reading exacerbates the feeling of
nausea.

Medication
In addition to checking any prescription or OTC medicines currently
being taken, the pharmacist should also enquire about any treatments
used in the past for motion sickness and their level of success or
failure.

Management
Prophylactic treatments for motion sickness, which can be bought
OTC, are effective and there is usually no need to refer patients to
the doctor.
Anticholinergic activity is thought to prevent motion sickness and
forms the basis of treatment by anticholinergic agents (e.g. hyoscine)
and antihistamines, which have anticholinergic actions (e.g. cinnarizine,
promethazine).

Antihistamines
Antihistamines include cinnarizine, meclozine and promethazine.
Anticholinergic effects are thought to be responsible for the effectiveness
of antihistamines in the prophylaxis of motion sickness. All have
the potential to cause drowsiness and promethazine appears to be the
most sedative. Meclozine and promethazine theoclate have long durations
of action and are useful for long journeys since they only need
to be taken once daily. Cinnarizine and promethazine theoclate are not
recommended for children younger than 5 years, whereas meclozine
can be given to those over 2 years. The manufacturers of products
containing these drugs advise that they are best avoided during pregnancy.

Anticholinergic agents
The only anticholinergic used widely in the prevention of motion
sickness is hyoscine hydrobromide, which can be given to children
over 3 years. Anticholinergic drugs can cause drowsiness, blurred
vision, dry mouth, constipation and urinary retention as side-effects,
although they are probably unlikely to do so at the doses used in OTC
formulations for motion sickness. Children could be given sweets to
suck to counteract any drying of the mouth.

Hyoscine has a short duration of action (from 1 to 3 h). It is
therefore suitable for shorter journeys and should be given 20 min
before the start of the journey. Anticholinergic drugs and antihistamines
with anticholinergic effects are best avoided in patients with
prostatic hypertrophy because of the possibility of urinary retention
and in glaucoma because the intraocular pressure might be increased.

Pharmacists should remember that side-effects from anticholinergic
agents are additive and may be increased in patients already taking
drugs with anticholinergic effects, such as amantidine, tricyclic antidepressants
(e.g. amitriptyline), butyrophenones (e.g. haloperidol) and
phenothiazines (e.g. chlorpromazine). It is therefore important for the
pharmacist to determine the identity of any medicines currently being
taken by the patient. Table 2 summarises recommended doses and
length of action for the treatments discussed.

Alternative approaches to motion sickness

Ginger
Some years ago it was found that ginger powder (Zingiber officinale)
could effectively reduce motion sickness. No mechanism of action has
been identified but it has been suggested that ginger acts on the GI
tract itself rather than on the vomiting centre in the brain or on the
vestibular system. No official dosage level has been suggested but

several proprietary products containing ginger are available. Ginger
would be worth trying for a driver who suffered from motion sickness,
since it does not cause drowsiness, and might be worth considering for
use in pregnant women, for whom other antiemetics such as anticholinergics
and antihistamines are not recommended. Ginger has been
shown to be effective in a research trial in nausea and vomiting
associated with pregnancy (see ‘Women’s Health’).

Acupressure wristbands
Following their apparently successful use on board naval ships to
reduce motion sickness, elasticated wristbands that apply pressure to
a defined point on the inside of the wrists are now readily available. As
yet there is no consistent evidence from clinical trials of the effectiveness
of this method but research is continuing. Such wristbands might
be worth trying for drivers or pregnant women.