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Diphenhydramine with dextromethorphan oral


Oral solution containing diphenhydramine with dextromethorphan

Drugs List

  • diphenhydramine 10mg/5ml and dextromethorphan 6.65mg/5ml oral solution sugar-free
  • Therapeutic Indications


    Congestive symptoms associated with colds
    Symptomatic relief of dry irritating coughs



    15 ml at bedtime. Repeat after 6 hours if required.


    Children 12 years and over
    15 ml at bedtime. Repeat after 6 hours if required.

    Additional Dosage Information

    Covonia Hot Dose Cough & Cold syrup
    The manufacturer notes that the dose should be diluted with an equal amount of hot (not boiling) water. The liquid should be sipped within 10 minutes of dilution.


    Children under 12 years
    Productive cough
    Within 2 weeks of discontinuing MAOIs
    Hepatic impairment
    Hereditary fructose intolerance
    Respiratory failure

    Precautions and Warnings

    Atopy in children aged 12 to 18 years
    Benign prostatic hyperplasia
    CYP2D6 poor metaboliser genotype
    Epileptic disorder
    History of asthma
    History of drug misuse
    Narrow angle glaucoma
    Pyloroduodenal obstruction
    Severe cardiac disorder
    Urinary retention

    Advise patient ability to drive or operate machinery may be impaired
    Advise patient not to drive until they know how the medicine affects them
    Advise patient this medicine may be subject to driving restrictions
    Contains alcohol
    Oral solution with maltitol unsuitable in hereditary fructose intolerance
    Presentations with sorbitol unsuitable in hereditary fructose intolerance
    May potentiate effect of CNS depressants
    Should not be taken with other cough or cold medicine
    Advise patient that the effects of alcohol may be potentiated
    Advise patient to avoid alcohol during treatment
    Advise patient to consult a doctor if symptoms persist despite treatment
    Patients should not exceed recommended dose

    MHRA/CHM advice (February 2009)

    Cough and cold remedies containing dextromethorphan and diphenhydramine should no longer be used in children under 6 as the balance of benefits and risk has not been shown to be favourable.

    However, the MHRA/CHM also lists a number of combination products which are being phased out from the market for use in children under 12 years. This product is included on this list, therefore, it is not recommended for children up to the age of 12 years.

    MHRA/CHM advice (March 2008)

    Children should not be given more than one cough or cold preparation at a time because different brands may contain the same active ingredient; care should be taken to give the correct dose.

    Pregnancy and Lactation


    Diphenhydramine with dextromethorphan is contraindicated in pregnancy.

    Combination products containing ethanol should be avoided during pregnancy (Briggs et al, 2015).

    Dextromethorphan is widely used as a cough suppressant. It is considered safe for use during pregnancy and can be given during all trimesters. No increased incidence of congenital malformations or human teratogenicity have been found. It is not known if it crosses the placenta, but this is likely, given its low molecular weight.

    Animal data and most published human experience suggest that diphenhydramine does not cause complications in pregnancy. There is one report of a statistical association with cleft palate following first trimester exposure. Premature infants exposed within two weeks of birth may be at risk of toxicity.

    The use of all medication in pregnancy should be avoided whenever possible; particularly in the first trimester. Non-drug treatments should also be considered. When essential, a medication with the best safety record over time should be chosen, employing the lowest effective dose for the shortest possible time. Polypharmacy should be avoided. Teratogens taken in the pre-embryonic period, often quoted as lasting until 14 to 17 days post-conception, are believed to have an all-or-nothing effect. Where drugs have a short half-life, and when the date of conception is certain, this may allow women to be reassured where drug exposure has occurred within this time frame. Further advice may be available from the UK National Teratology Information Service (NTIS) and through ToxBase, available via password on the internet ( ) or if this is unavailable at the backup site ( ).


    Diphenhydramine with dextromethorphan is contraindicated in breastfeeding.

    Combination products containing ethanol should be avoided during breastfeeding (Briggs et al, 2015).

    Dextromethorphan has less sedative action than codeine. There is little data available on use during breastfeeding, but single doses are considered safe. Careful observation is required for repeated doses in case of somnolence. It is not known whether it is excreted in breast milk, but it is thought unlikely that transfer would occur in clinically significant amounts.

    Diphenhydramine should not be used during breastfeeding as small amounts of antihistamines are excreted in breast milk. Data is limited in humans but expected breast milk concentrations are not thought to be sufficiently high to affect a nursing infant.

    Neonates, infants born prematurely, those with low birth weight, those with an unstable gastrointestinal function or who have serious illnesses may require special consideration. For any infant, if a drug is prescribed to the nursing mother, it should be at the lowest practical dose and for the shortest time. When drug administration is unavoidable and breastfeeding is to continue, minimisation of exposure of the infant to the drug may sometimes be achieved by timing the maternal doses to just after a feeding episode. Infants exposed to drugs via breast milk should be monitored for unusual signs or symptoms. Interactions between the drug received by the infant from the mother's milk and medication prescribed for the infant should also be considered, for example, when the drug given to the infant may prevent metabolism of the drug received via breast milk.
    Specialist advice is available from the UK Drugs in Lactation Advisory Service at

    Effects on Ability to Drive and Operate Machinery

    This class of medicine is in the list of drugs included in regulations under 5a of the Road Traffic Act 1988 (England and Wales). When prescribing this medicine: Advise patient the medicine can affect cognitive function and is likely to affect ability to drive. Advise patient not to drive until they know how the medicine affects them.

    Side Effects

    Blood disorders
    Blurred vision
    Dry mouth
    Extrapyramidal effects
    Gastro-intestinal symptoms
    Haemolytic anaemia
    Hair loss
    Hepatic impairment
    Hypersensitivity reactions
    Impaired concentration
    Paradoxical reactions
    Psychomotor impairment
    Respiratory depression
    Sleep disturbances
    Thickening of bronchial secretions
    Urinary retention


    It is strongly recommended that the UK National Poisons Information Service be consulted on cases of suspected or actual overdose where there is doubt over the degree of risk or about appropriate management.

    The following number will direct the caller to the relevant local centre (0844) 892 0111

    Information may be obtained if you have access to ToxBase the primary clinical toxicology database of the National Poisons Information Service. This is available via password on the internet ( ) or if this is unavailable at the backup site ( ).

    Further Information

    Last Full Review Date: May 2017

    Reference Sources

    Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 10th edition (2015) ed. Briggs, G., Freeman, R. Wolters Kluwer Health, Philadelphia.
    Medications and Mothers' Milk, Sixteenth Edition (2014) Hale, T and Rowe, H, Hale Publishing, Plano, Texas.

    Summary of Product Characteristics: Covonia Hot Dose Cough & Cold Syrup. Thornton & Ross Ltd. Revised November 2016.

    Summary of Product Characteristics: Covonia Night Time Formula. Thornton & Ross Ltd. Revised November 2016.

    Dear Healthcare Professional Letter. Medicines and Healthcare products Regulatory Agency. 28th February 2009.
    Last accessed: 16 May 2017 Government departments. Department for Transport. Publications. Drug driving and medicine: Advice for healthcare professionals. Drug driving: Guidance for healthcare professionals on drug driving. Available at: Last accessed: 16 May 2017
    New drug driving offence implications for medicines packaging. Medicines Regulatory News. 10 December 2013. Available at: Last accessed: 16 May 2017

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