Strong opioid + antihistamine antiemetic Pregnancy: §4.6: there is no evidence on the safety of the combination in human pregnancy, nor evidence from animal work that the constituents are free from hazard; limited epidemiological data on cyclizine and morphine found no evidence of teratogenicity, but in the absence of definitive human data the use of this combination in pregnancy is not advised. Regular use during pregnancy may cause drug dependence in the foetus, leading to neonatal withdrawal symptoms - advise the patient of the risk of neonatal opioid withdrawal syndrome and ensure appropriate treatment will be available. Administration during labour may depress neonatal respiration and an antidote for the child should be readily available. Breast-feeding: administration to nursing women is not recommended as dipipanone may be secreted in breast milk and may cause respiratory depression in the infant; cyclizine is excreted in human milk (amount not quantified) and opioids can significantly suppress lactation.

Dipipanone hydrochloride with cyclizine

Brand names: Diconal

Dipipanone with cyclizine is a combination of an opioid analgesic and an antihistamine antiemetic used for moderate-to-severe pain.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: One tablet (dipipanone hydrochloride 10 mg with cyclizine 30 mg)

Route: Oral

Frequency: Every 6 hours (initial dose in all conditions)

Max: It is seldom necessary to exceed a dose of 30 mg dipipanone given 6-hourly (i.e. 12 tablets in 24 hours)

eMC §4.2 (Diconal 10 mg + 30 mg Tablets, UK SPC; strengths taken from the product name). The initial dose in all conditions is one tablet every 6 hours and 'it is unwise to exceed this dose in view of the difficulty in accurately predicting the initial central effects of dipipanone'. Should this dose fail to provide adequate analgesia, as in severe intractable pain or when other potent opioids have been used, it may be increased by half a tablet every six hours. Prior to starting treatment a discussion should be held with the patient to put in place a strategy for ending treatment, to minimise the risk of addiction and drug withdrawal syndrome (§4.2, §4.4); drug withdrawal syndrome may occur on abrupt cessation or dose reduction, so taper gradually when therapy is no longer required - tapering from a high dose may take weeks to months. ELDERLY: no specific information on use in elderly patients; in common with opioid drugs it may be expected to cause confusion in this age group and careful monitoring is advised. PAEDIATRIC: 'There is no specific information on the use of Diconal in children. Diconal is very rarely indicated in children and dosage guidelines cannot be stated.' No paediatric dose exists in this SPC - verify any under-18 use against a children's formulary. §4.4 also advises caution (including consideration of dose administered) in convulsive disorders, delirium tremens, hypothyroidism, adrenocortical insufficiency, hypopituitarism, prostatic hypertrophy, shock, diabetes mellitus, and in debilitated patients who may be more sensitive to respiratory depressant effects; §4.4 was truncated at source fetch so the clinician should review it in full.

Dose adjustments

Renal

§4.3 lists severe renal impairment as a contraindication. No numeric renal dose adjustment is stated in the captured posology.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients (§4.3)
Respiratory depression, especially with cyanosis and excessive bronchial secretions; obstructive airway disease, an attack of bronchial asthma, or heart failure secondary to chronic lung disease (§4.3)
Head injury and raised intracranial pressure (§4.3)
Acute alcohol intoxication - the anti-emetic properties of cyclizine may increase the toxicity of alcohol (§4.3)
Individuals receiving monoamine oxidase inhibitors, or within 14 days of stopping such treatment (§4.3)
Ulcerative colitis (may precipitate toxic dilatation or spasm of the colon); paralytic ileus and delayed gastric emptying; spasm of the biliary or renal tract, particularly immediately after operative interventions on the biliary tract (§4.3)
Pre-operative period or during the first 24 hours post-operatively (§4.3)
Severe hepatic impairment (may precipitate hepatic encephalopathy or coma) and severe renal impairment (§4.3)

Side effects

Dipipanone: respiratory depression, respiratory failure, bronchospasm, pulmonary oedema (frequency not known)
Dipipanone: constipation, nausea, vomiting, abdominal pain, ileus, dyspepsia, dry mouth, exacerbation of pancreatitis (frequency not known)
Dipipanone: somnolence, sedation, dizziness, convulsions, syncope, coma, headache, myoclonus, raised intracranial pressure, miosis (frequency not known)
Dipipanone: drug dependence, drug tolerance and drug withdrawal syndrome (withdrawal syndrome uncommon); confusion, mood changes, euphoria, dysphoria, psychosis, agitation, hallucinations, decreased libido (frequency not known); hypotension, hypertension, orthostatic hypotension, tachycardia, bradycardia, circulatory failure (frequency not known)
Cyclizine: agranulocytosis, leucopenia, haemolytic anaemia and thrombocytopenia; hypersensitivity reactions including anaphylaxis; disorientation, restlessness or agitation, nervousness, euphoria, insomnia and auditory and visual hallucinations, particularly when dosage recommendations have been exceeded (frequency not known). The §4.8 cyclizine table was truncated at source fetch

Interactions

Monoamine oxidase inhibitors - contraindicated in individuals receiving MAOIs, or within 14 days of stopping such treatment (§4.3)
Alcohol - acute alcohol intoxication is a contraindication and the anti-emetic properties of cyclizine may increase the toxicity of alcohol (§4.3); §4.4 states concomitant use of alcohol may increase the undesirable effects and should be avoided
The eMC §4.5 interaction section was not captured in this bundle (the fetch was truncated within §4.4) - clinician to review §4.5 in the full SPC

Clinical monograph

How it works

Dipipanone is an opioid agonist that relieves pain through opioid receptors, while cyclizine is an antihistamine with antiemetic and antimuscarinic properties intended to counter opioid-induced nausea.

Prescribing in practice

The fixed combination is generally not recommended for prolonged use or palliative care because the opioid dose cannot be increased without also raising the cyclizine dose, and cyclizine can cause adverse cardiac and antimuscarinic effects and is associated with misuse.
As it contains an opioid it carries the usual risks of respiratory depression, dependence and constipation, and controlled drug requirements apply.
The cyclizine component adds sedation and antimuscarinic effects, so caution applies in conditions such as urinary retention, glaucoma and in the elderly.

Monitoring

Monitor analgesic response, sedation, respiratory function and antimuscarinic effects, bearing in mind the constraints of the fixed-dose combination.

Counselling the patient

It may cause marked drowsiness; do not drive or operate machinery if affected.
Avoid alcohol while taking it.
Report inadequate pain relief rather than taking extra, as the dose cannot be increased freely.

Evidence & guidelines

Its place in therapy is informed by long-standing clinical experience and prescribing guidance that limits its use compared with single-agent opioids.

Reference: FPM Opioids Aware; MDR Schedule 2; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways