Benylin Mucus Cough Night

Summary of Product Characteristics Updated 08-Feb-2024 | McNeil Products Ltd

1. Name of the medicinal product

Benylin Dual Action Night Cough & Congestion

Benylin Mucus Cough Night

2. Qualitative and quantitative composition

Each 5 ml contains Diphenhydramine hydrochloride 14 mg, Guaifenesin 100 mg and Levomenthol 1.1 mg.

Also contains:







Ponceau 4R




Sodium Benzoate


For the full list of excipients, see section 6.1.

3. Pharmaceutical form

A clear red syrup with no insoluble matter.

4. Clinical particulars
4.1 Therapeutic indications

For the relief of cough (dry and/or chesty), associated congestive symptoms and aiding restful sleep.

4.2 Posology and method of administration


Adults and children aged 12 years and over:

Two 5 ml spoonfuls four times a day.

Or to aid sleep patients may start with two 5 ml spoonfuls at bedtime followed by two 5 ml spoonfuls every 6 hours.

Do not take more than 4 doses (1 dose = two 5 ml spoonfuls) in 24 hours.

Children under 12 years:

This medicine is contraindicated in children under the age of 12 years (see section 4.3).

Elderly (over 65 years):

As for adults.

Do not exceed the stated dose.

Keep out of the sight and reach of children.

Method of Administration

For oral use

4.3 Contraindications

This product is contraindicated in individuals with hypersensitivity to diphenhydramine, guaifenesin, levomenthol or to any of the excipients listed in section 6.1.

This product should not be administered to patients currently receiving monoamine oxidase inhibitors (MAOIs) or within 14 days of of stopping trreatment (see section 4.5).

Not to be used in children under the age of 12 years.

4.4 Special warnings and precautions for use

This product may cause drowsiness. This product should not be used to sedate a child.

Subjects with moderate to severe renal dysfunction or hepatic disease should exercise caution when using this product (see section 5.2).

Do not use with any other product containing diphenhydramine including topical formulations used on large areas of skin.

Diphenhydramine may enhance the sedative effects of central nervous system depressants, including alcohol, opioid analgesics, antipsychotics, sedatives and tranquilizers. Patients should be advised while taking this product to avoid alcoholic beverages and consult a healthcare professional prior to taking with central nervous system depressants (see section 4.5).

Excitability may occur.

Patients with the following conditions should be advised to consult a physician before using this product:

• Acute or chronic bronchial asthma, a persistent or chronic cough such as occurs with smoking, chronic bronchitis or emphysema or where cough is accompanied by excessive secretions

• Susceptibility to angle-closure glaucoma

• Prostatic hypertrophy and/or urinary retention

If symptoms persist or get worse, or if new symptoms occur, patients should stop use and consult a physician.

Do not take with a cough suppressant.

This product contains sucrose. Patients with rare hereditary problems of fructose intolerance, glucose-galactose malabsorption or sucrase-isomaltase insufficiency should not take this medicine.

This product contains 7 g glucose and 2 g sucrose per 10 ml dose. This should be taken into account in patients with diabetes mellitus. Patients with rare glucose-galactose malabsorption should not take this medicine.

This product contains Ponceau 4R (E124) red colouring which may cause allergic reactions.

This medicinal product contains 5 vol % ethanol (alcohol), i.e. up to 196.62 mg per 5ml dose, which is equivalent to less than 5 ml beer, 2 ml wine per 5 ml dose. The small amount of alcohol in this medicine will not have any noticeable effects.

This medicinal product contains 18.53 mg sodium per 5ml dose, equivalent to 1.853% of the WHO recommended maximum daily intake of 2 g sodium for an adult.This product contains 8.47 mg benzoic acid in 5ml dose.

The label contains the following statements:

May cause drowsiness. If affected, do not drive, cycle or operate machinery.

Do not use to sedate a child.

Talk to your doctor or pharmacist:

If you suffer from a chronic or persistent cough, if you have asthma, suffering from an acute asthmatic attack or where cough is accompanied by excessive secretions.

If your cough lasts for more than 5 days, comes back, or is accompanies by a fever, rash or persistent headache.

Avoid alcoholic drink. Do not use if bottle seal is broken when purchased. Keep bottle tightly closed. Do not store above 30° C. Keep out of the sight and reach of children. As with all medicines, if you are pregnant consult your doctor or pharmacist before taking this product.

4.5 Interaction with other medicinal products and other forms of interaction


CNS depressants: May enhance the sedative effects of CNS depressants including barbiturates, hypnotics, opioid analgesics, antipsychotics and alcohol.

Antimuscarinic drugs: May have an additive muscarinic action with other drugs such as atropine and some antidepressants This may result in tachycardia, dry mouth, gastrointestinal disturbances (e.g. colic), urinary retention and headache.

MAOIs: This product should not to be used in patients taking MAOIs or within 14 days of stopping treatment as there is a risk of serotonin syndrome.


Interference with diagnostic tests: If urine is collected within 24 hours of a dose of this product a metabolite of guaifenesin may cause a colour interference with laboratory determinations of urinary 5-hydroxyindole acetic acid (5-HIAA) and vanillylmandelic acid (VMA).

4.6. Fertility, pregnancy and lactation

Insufficient information is available on the effects of administration of this product during human pregnancy. This product should not be used during pregnancy or lactation unless the potential benefit of treatment to the mother outweighs the possible risks to the developing foetus or breastfeeding infant.


There are no adequate and well-controlled studies of diphenhydramine in pregnant or breast-feeding women. Diphenhydramine crosses the placenta and is excreted into breast milk, but levels have not been reported.


Guaifenesin is excreted in breast milk in small amounts with no effect expected on the infant.


There are no adequate and well-controlled studies of menthol in pregnant women. Menthol is excreted in breast milk; when 100 mg of menthol was ingested, there was up to 5.87 ug/L of menthol in breast milk.

4.7 Effects on ability to drive and use machines

This preparation may cause drowsiness. If affected, the patient should not drive or operate machinery.

4.8 Undesirable effects

Adverse drug reactions (ADRs) identified during clinical trials and post-marketing experience with diphenhydramine, guaifenesin, levomenthol or the combination are included in the table below by System Organ Class (SOC). The frequencies are provided according to the following convention:

Very common ≥ 1/10

Common ≥ 1/100 and < 1/10

Uncommon ≥ 1/1,000 and <1/100

Rare ≥ 1/10,000 and <1/1,000

Very rare <1/10,000

Not known (cannot be estimated from the available data)

ADRs are presented by frequency category based on 1) incidence in adequately designed clinical trials or epidemiology studies, if available, or 2) when incidence cannot be estimated, frequency category is listed as 'Not known'.

System Organ Class (SOC)


Adverse Drug Reaction

(Preferred Term)

Blood and Lymphatic System


Blood disorder1

Immune System Disorders



Not known


Psychiatric Disorders







Confusional state1


Sleep disorder1

Not known


Nervous System Disorders

Very common

Somnolence (usually diminishes within a few days)*





Paradoxical stimulation

Psychomotor impairment1



Extrapyramidal disorder1


Not known

Coordination abnormal1


Eye Disorders


Blurred Vision1

Ear and Labyrinth Disorders



Cardiac Disorders




Not known


Vascular Disorders



Respiratory, Thoracic and Mediastinal Disorders


Dry throat1

Increased viscosity of bronchial secretion1

Not known

Nasal dryness1

Gastrointestinal Disorders


Dry mouth*

Gastrointestinal disorder1

Not known

Abdominal discomfort2

Abdominal pain upper2


Diarrhoea1, 2


Nausea 1,2

Vomiting 1,2

Hepatobiliary Disorders


Liver Disorder1

Skin and Subcutaneous Tissue Disorders



Not known




Renal and Urinary Disorders


Urinary retention1

Not known


General Disorders and Administration Site Conditions



Not known

Chest discomfort

* Frequency category based on clinical trials with single-ingredient diphenhydramine.

1 Associated with diphenhydramine

2 Associated with guaifenesin


Adverse reactions to levomenthol at the low concentration present in the product are not anticipated.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme at: or search for MHRA Yellow Card in the Google Play or Apple App Store.

4.9 Overdose


Following overdose in adults, moderate symptoms have been associated with ingestions of greater than 300-500 mg and serious symptoms associated with doses greater than 1 g diphenhydramine.

Young children may be more sensitive to the effects of overdose.

Mild to Moderate Symptoms:

Somnolence, anticholinergic syndrome (mydriasis, flushing, fever, tachycardia, dry mouth, urinary retention, decreased bowel sounds, agitation confusion and hallucinations), mild hypertension, nausea and vomiting are common after overdose.

Severe Symptoms:

Effects may include delirium, psychosis, seizures, coma, hypotension, QRS widening, and ventricular dysrhythmias (including torsades de pointes), but are generally only reported in adults after large ingestions. Rhabdomyolysis and renal failure may rarely develop in patients with prolonged agitation, coma, or seizure. Death may occur as a result of respiratory failure or circulatory collapse.


Somnolence may be associated with guaifenesin overdose.

When taken in excess, guaifenesin may cause renal calculi.


Excessive use of menthol may lead to abdominal pain, vomiting, flushed face, dizziness, weakness, tachycardia, stupor, and ataxia.


Gastric lavage in the conscious patient and intensive supportive therapy where necessary, as with cases of overdose with antihistaminic drugs.

5. Pharmacological properties
5.1 Pharmacodynamic properties

Pharmacotherapeutic group: Other cough suppressants and expectorants

ATC code: R05FB

Diphenhydramine is a potent antihistamine and antitussive with anticholinergic and sedative properties. Recent experiments have shown that the antitussive action is discrete from H1-receptor blockade and is located in the brain stem.

Guaifenesin is reported to reduce the viscosity of tenacious sputum and is used as an expectorant.

Levomenthol has mild local anaesthetic and decongestant properties.

5.2 Pharmacokinetic properties

Diphenhydramine is well absorbed in the gastro-intestinal tract. Peak serum levels are reached at between 2 - 2.5 hours after an oral dose. Duration of activity is between 4 - 8 hours. The drug is widely distributed throughout the body, including the CNS, and some 78% is bound to plasma proteins. Estimates of the volume of distribution lie in the range 3.3 - 6.8 l/kg.

Diphenhydramine experiences extensive first-pass metabolism, undergoing two successive N-Demethylations; the resultant amine is then oxidised to a carboxylic acid. Values for plasma clearance lie in the range 600 - 1300 ml/min and the terminal elimination half life lies in the range 3.4 - 9.3 hours. Little unchanged drug is excreted in the urine.

Pharmacokinetic studies in elderly subjects indicate no major differences in drug distribution or elimination compared with younger adults.

Guaifenesin is readily absorbed after oral administration. It is rapidly metabolised by oxidation to β -(2-methyoxy-phenoxy) lactic acid. About 40% of a dose is excreted as this metabolite in the urine in 3 hours.

After absorption Levomenthol is conjugated in the liver and excreted both in the urine and bile as the glucuronide.

Renal Dysfunction

The results of a review on the use of diphenhydramine in renal failure suggest that in moderate to severe renal failure, the dose interval should be extended by a period dependant on glomerular filtration rate (GFR)

Hepatic Dysfunction

After intravenous administration of 0.8 mg/kg Diphenhydramine, a prolonged half-life was noted in patients with chronic liver disease which correlated with the severity of the disease. However, the mean plasma clearance and apparent volume of distribution were not significantly affected.

5.3 Preclinical safety data

There are no pre-clinical data of relevance to the prescriber which are additional to those already included in other sections of the SPC.

6. Pharmaceutical particulars
6.1 List of excipients

Sodium benzoate (E211)


Glucose liquid


Citric acid monohydrate

Sodium citrate

Saccharin sodium

Ethanol 96%

Caramel (E150d)

Ponceau 4R (E124)

Concentrated raspberry essence

Natural sweetness enhancer


Purified water

6.2 Incompatibilities

Not applicable

6.3 Shelf life

3 years

6.4 Special precautions for storage

Do not store above 25° C. Do not refrigerate or freeze.

6.5 Nature and contents of container

125, 150 or 300 ml amber glass bottles with a 2 piece plastic child resistant, tamper evident closure fitted with a polyterephtalate ethylene faced aluminium/expanded polyethylene laminated wad

6.6 Special precautions for disposal and other handling

No special requirements.

Any unused product or waste material should be disposed of in accordance with local requirements.

7. Marketing authorisation holder

McNeil Products Limited

50 – 100 Holmers Farm Way

High Wycombe


HP12 4EG

United Kingdom

8. Marketing authorisation number(s)

PL 15513/0050

9. Date of first authorisation/renewal of the authorisation

16 June 1997 / 27 July 2001

10. Date of revision of the text


Company Contact Details
McNeil Products Ltd

50-100 Holmers Farm Way, High Wycombe, HP12 4EG, UK

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0808 238 9999 (freephone)