Drugs used for nausea and labyrinth disorders not listed below:

• Haloperidol (see 4.2.1 Antipsychotic drugs)
• Lorazepam (see 4.8.2 Drugs used in status epilepticus)
• Promethazine (see 3.4.1 Antihistamines)
• Levomepromazine (see 4.2.1 Antipsychotic drugs)

Vomiting is a complicated process mediated by a central coordinating 'vomiting center', which is located in the brain stem. The vomiting center receives input via the nervous system from many sources, including the chemoreceptor trigger zone (CTZ), the pharynx, the gastrointestinal tract, pain receptors and the vestibular apparatus. CTZ activity is modified by a variety of receptors, including histaminic, muscarinic and serotonergic. Most antiemetic drugs have antagonist activity at one or more of these receptors.

Anti-emetics should be prescribed only when the cause of vomiting is known, particularly in children, otherwise the symptomatic relief that they produce may delay diagnosis. Anti-emetics are unnecessary and sometimes harmful when the cause can be treated e.g. diabetic ketoacidosis, or in excessive digoxin or anti-epileptic dosage.

Antihistamines

Cinnarizine

• Tablets 15mg (£10.00 = 30mg three times daily)

Indications

• Vestibular disorders, such as vertigo, tinnitus, nausea and vomiting in Ménière's disease
• Motion sickness

Dose

• Vestibular disorders, 30mg three times daily
• Motion sickness, 30mg 2 hours before travel then 15mg every 8 hours during journey if necessary

Cyclizine

• Tablets 50mg (£3.32 = 50mg three times a day)
• Solution for injection 50mg/1ml (£1.61 = 1ml ampoule)

Indications

• Nausea, vomiting, vertigo, motion sickness, labyrinthine disorders
• Palliative care guidance
• Nausea and vomiting in pregnancy and hyperemesis gravidarum (off-label)

Dose

• Oral: 50mg up to 3 times daily
• Intramuscular or intravenous injection: 50mg 3 times daily

Notes

1. Avoid cyclizine in patients with severe heart disease. Cyclizine may be associated with tachycardia.

Doxylamine / pyridoxine

• Gastro-resistant tablets 10mg/10mg (£39.90 = 10mg/10mg four times a day for one week)

Indications and dose

• Nausea and vomiting in pregnancy in adults over 18 years of age:
  • two tablets once daily at bedtime for 2 days,
  • increased on day 3 if necessary to one tablet in the morning and two tablets at bedtime,
  • further increased on day 4 if necessary to one tablet in the morning, one tablet mid-afternoon and two tablets at bedtime. (Maximum four tablets per day).

Notes

1. Doxylamine/pyridoxine is considerably more expensive than other antiemetics that have long been used off-label for nausea and vomiting in pregnancy (NVP) but is the only licensed product for NVP in the UK.
2. Doxylamine/pyridoxine should be administered on an empty stomach with a glass of water.
3. Doxylamine/pyridoxine has anticholinergic properties and therefore should be used with caution in specific patient groups, refer to SmPC.
4. Concomitant treatment with MAOIs is contraindicated (anticholinergic effects prolonged and intensified by MAOIs).
5. Continued need should be reassessed as the pregnancy progresses. To prevent a sudden return of NVP symptoms, the SmPC recommends a gradual tapering dose at the time of discontinuation.

Phenothiazines and related drugs

Prochlorperazine

• Tablets 5mg (£0.61 = 10 tablets)
• Buccal tablets 3mg (£1.67 = 10 tablets)
• Solution for injection 12.5mg/1ml (£0.52 = 1ml ampoule)

Indications and dose

• Nausea and vomiting:
  • Adult: acute attack:
    • Oral tablets: Initially 20 mg for 1 dose, then 10 mg for 1 dose, to be given 2 hours after first dose.
    • Deep intramuscular injection: 12.5 mg as required, to be followed if necessary after 6 hours by an oral dose.
  • Adult: prevention:
    • Oral tablets: 5-10mg two to three times a day.
    • Deep intramuscular injection: 12.5 mg as required, to be followed if necessary after 6 hours by an oral dose.
• Nausea and vomiting in pregnancy and hyperemesis gravidarum (second line) (off-label):
  • Oral tablets: 5-10mg up to three times a day.
  • Buccal tablets: 3-6mg twice daily.

Notes

1. Prochlorperazine buccal tablets have been included only for use as an alternative to injection in certain circumstances (e.g. GP call out). They should be prescribed in small quantities not exceeding 10 tablets.
2. Severe reactions to prochlorperazine should be treated with procyclidine injection, 5mg to 10mg given IM, repeated if necessary after 20 minutes, maximum of 20mg daily. In children, the dose range is as follows: Age 1-2yrs, 500 micrograms to 2mg, age 2-12yrs 2mg to 5mg, and age 12-18yrs 5mg to 10mg. Subsequent oral doses may be needed for the next 2 or 3 days.
3. Prochlorperazine should not be prescribed for patients with Parkinson's disease and should be used with caution in the elderly
4. Balance disorders can be exacerbated, in part, by the use of labyrinthine sedatives. These drugs, when used for acute vertigo, should only be given for a maximum of two weeks.

Droperidol

• Solution for injection ampoules 2.5mg/1ml (1ml)

Domperidone and metoclopramide

Domperidone

• Tablets 10mg (£0.46 = 10mg three times daily, 7 days treatment)
• Oral suspension sugar free 1mg/ml (£49.32 = 200ml)

Indications

• Nausea and vomiting
• Palliative care guidance

Dose

• Adults and adolescents 12 years or older and weighing 35kg or more, 10mg up to 3 times daily; maximum 30mg daily

Notes

1. Domperidone does not readily cross the blood-brain barrier and is therefore the preferred option for Parkinson's patients. It may also be useful in reducing the side effects of levodopa and bromocriptine.
2. MHRA Safety Update (December 2019): Domperidone for nausea and vomiting: lack of efficacy in children; reminder of contraindications in adults and adolescents
   1. Change of indication:
      1. domperidone is now authorised for the relief of symptoms of nausea and vomiting only in adults and adolescents 12 years of age or older and weighing 35 kg or more
      2. consider alternative treatments to domperidone in children younger than 12 years of age who need relief of symptoms of nausea and vomiting
   2. Dose and treatment duration:
      1. Domperidone should be used at the lowest effective dose for the shortest possible duration. Maximum treatment duration should not usually exceed 1 week
   3. Domperidone is contraindicated in patients:
      1. with moderate to severe hepatic impairment
      2. with known existing prolongation of cardiac conduction intervals (particularly QTc)
      3. with underlying cardiac diseases such as congestive heart failure
      4. with significant electrolyte disturbances
      5. receiving QT-prolonging drugs (for considerations with regard to apomorphine (see Drug Safety Update April 2016)
      6. receiving potent CYP3A4 inhibitors (regardless of their QT-prolonging effects)
      7. with hypersensitivity to domperidone
      8. with a prolactin-releasing pituitary tumour
      9. in which stimulation of the gastric motility could be harmful (for example, in patients with gastro-intestinal haemorrhage, mechanical obstruction, or perforation)

Metoclopramide

• Tablets 10mg (£3.24 = 10mg three times a day)
• Oral solution sugar free 5mg/5ml (£13.24 = 150ml)
• Solution for injection 10mg/2ml (£0.54 = 2ml ampoule)

Indications and dose

• Symptomatic treatment of nausea and vomiting:
  • Adults: the maximum dose in 24 hours is 30 mg (or 0.5 mg per kg bodyweight) in three divided doses (see note 1)
• Palliative care guidance
• Nausea and vomiting in pregnancy and hyperemesis gravidarum (second line) (off-label):
  • Adults: 5-10mg three times a day for a maximum of 5 days (not for patients under 20 years old)

Notes

1. MHRA Drug Safety Update (August 2013): Metoclopramide: risk of neurological adverse effects - restricted dose and duration of use. The benefits and risks of metoclopramide have been reviewed by the European Medicines Agency's Committee on Medicinal Products for Human Use, which concluded that the risk of neurological effects such as extrapyramidal disorders and tardive dyskinesia outweigh the benefits in long-term or high-dose treatment. To help minimise the risk of potentially serious neurological adverse effects, the following restrictions to indications, dose, and duration of use have been made:
   1. In adults over 18 years, metoclopramide should only be used for prevention of postoperative nausea and vomiting, radiotherapy-induced nausea and vomiting, delayed (but not acute) chemotherapy-induced nausea and vomiting, and symptomatic treatment of nausea and vomiting, including that associated with acute migraine (where it may also be used to improve absorption of oral analgesics);
   2. Metoclopramide should only be prescribed for short-term use (up to 5 days);
   3. Usual dose is 10 mg, repeated up to 3 times daily; max. daily dose is 500 micrograms/kg;
   4. Intravenous doses should be administered as a slow bolus over at least 3 minutes;
   5. Oral liquid formulations should be given via an appropriately designed, graduated oral syringe to ensure dose accuracy.

5HT3-receptor antagonists

Ondansetron

• Tablets 4mg, 8mg (£2.89 = 8mg twice daily, 5 days treatment)
• Oral solution sugar free 4mg/5ml (£23.16 = 50ml bottle)
• Solution for injection ampoules 4mg/2ml, 8mg/4ml

Indications

• Nausea and vomiting induced by cytotoxic chemotherapy and radiotherapy
• Prevention and treatment of post-operative nausea and vomiting
• Nausea and vomiting in pregnancy and Hyperemesis Gravidarum (off-label)

Notes

1. MHRA Drug safety update (August 2012): Ondansetron (Zofran): important new intravenous dose restriction
   1. A single dose of intravenous ondansetron given for the management of chemotherapy-induced nausea and vomiting (CINV) in adults must not exceed 16 mg (infused over at least 15 minutes).
   2. Ondansetron should be avoided in patients with congenital long QT syndrome.
   3. Caution must be used if administering ondansetron to patients with risk factors for QT interval prolongation or cardiac arrhythmias. These include: electrolyte abnormalities; use of other medicines that prolong the QT interval (including cytotoxic drugs) or may lead to electrolyte abnormalities; congestive heart failure; bradyarrhythmias; and use of medicines which lower the heart rate.
   4. Hypokalemia and hypomagnesemia should be corrected prior to ondansetron administration.
2. MHRA Drug Safety update (July 2013): Ondansetron for intravenous use: dose-dependent QT interval prolongation
   1. In patients age 75 years or older a single dose of intravenous ondansetron for the prevention of CINV must not exceed 8 mg (infused over at least 15 minutes).
   2. In adult patients younger than 75 years a single dose of intravenous ondansetron for prevention of CINV must not exceed 16 mg (infused over at least 15 minutes).
   3. Dilution and administration in patients age 65 years or older:
      1. all intravenous doses for prevention of CINV should be diluted in 50–100 mL saline or other compatible fluid and infused over at least 15 minutes.
   4. Repeat dosing in all adults (including elderly patients):
      1. repeat intravenous doses of ondansetron should be given no less than 4 hours apart.
3. MHRA Drug Safety Update (January 2020): Ondansetron: small increased risk of oral clefts following use in the first 12 weeks of pregnancy.
   1. Patients must be counselled regarding the benefits of ondansetron together with the small increase in risk of orofacial cleft following use in the first 12 weeks of pregnancy. The background risk for orofacial cleft is 11 per 10,000 pregnancies. The risk of orofacial cleft is 14 per 10,000 pregnancies following ondansetron use in the first trimester. This equates to an additional 3 cases of orofacial cleft per 10,000 pregnancies exposed to ondansetron.

Granisetron

• Tablets 1mg (£4.19 = 1mg dose)
• Solution for injection 1mg/1ml (£2.42 = 1ml ampoule)

Hyoscine

Hyoscine hydrobromide

• Tablets 300micrograms (£1.84 = 12 tablets)
• Transdermal patches 1mg/72hours (£12.87 = 2 patches)
• Solution for injection ampoules 400micrograms/1ml

Notes

1. For motion sickness: Give 30 minutes before travel, followed by two subsequent doses.
2. MHRA Drug Safety Update (July 2023): Hyoscine hydrobromide patches (Scopoderm 1.5mg Patch or Scopoderm TTS Patch): risk of anticholinergic side effects, including hyperthermia
   1. Be alert to the potential for anticholinergic side effects in patients, particularly if used outside the licence. 
   2. Children and elderly patients are more susceptible to anticholinergic toxicity. Serious effects can include hyperthermia, urinary retention, delirium, hallucinations, seizures, coma, and respiratory paralysis.
   3. In hospital or residential care settings, monitor patients for signs and symptoms of anticholinergic side effects and manage promptly.
   4. If used at home, counsel patients, parents, and carers on side effects to be aware of and what to do if they occur (see the safety update).

Other drugs for Meniere's disease

Betahistine dihydrochloride

• Tablets 8mg, 16mg (£4.48 = 16mg three times daily)

Indications

• Ménière's disease

Dose

• Initially 16mg 3 times daily, preferably with food; maintenance 24–48mg daily