Summary of Product Characteristics Updated 30-Sep-2026 | McNeil Products Ltd
Benylin Mucus Cough Max Menthol flavour 100 mg/5 ml Oral Solution
This product contains 20 mg guaifenesin in each ml (100 mg in 5 ml).
Excipient(s) with known effect
| Ethanol Ponceau 4R (E124) | 39.7 mg/ml 0.05 mg/ml |
| Macrogol glycerol hydroxystearate 40 Sodium benzoate (E211) Propylene glycol (E1520) | 3.0 mg/ml 1 mg/ml 200.35 mg/ml |
For the full list of excipients, see section 6.1.
Oral solution
Clear to slightly opalescent red liquid
Benylin Mucus Cough Max Menthol Flavour 100 mg/ 5 ml Oral Solution is indicated to help loosen phlegm and thin bronchial secretions associated with productive cough, for use in adults and adolescents over 12 years.
Posology
Adults and adolescents over 12 years:
10 ml (200 mg guaifenesin) 4 times a day.
Maximum daily dose: 40 ml (800 mg guaifenesin)
Paediatric population
The safety and efficacy of Benylin Mucus Cough Max Menthol Flavour 100 mg/5 ml Oral Solution in children under 12 years of age has not yet been established.
No data are available.
Elderly:
As per adults.
Hepatic/renal impairment
Caution should be exercised in severe hepatic and severe renal impairment (see Section 5.2).
If cough persists for more than 7 days, tends to recur, or is accompanied by a fever, rash, or persistent headache, a physician should be consulted.
Method of administration
Oral
Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.
This product should not be used for persistent or chronic cough, such as occurs with asthma, or where cough is accompanied by excessive secretions, unless directed by a physician.
A persistent cough may be a sign of a serious condition. If cough persists for more than 7 days, tends to recur, or is accompanied by a fever, rash, or persistent headache, a physician should be consulted.
Caution should be exercised when using the product in the presence of severe renal or severe hepatic impairment.
The concomitant use of cough suppressants is not recommended.
This medicinal product contains 10 mg of benzoate salt in each 10 ml dose.
This medicinal product may contain very trace amounts of glucose. Patients with rare glucose galactose malabsorption should not take this medicine.
This medicinal product contains 381 mg of alcohol (ethanol) in each 10 ml dose which is equivalent to 38.1 mg/ml. The amount in 10 ml of this medicine is equivalent to 9.5 ml beer or 3.8 ml wine. The small amount of alcohol in this medicine will not have any noticeable effects.
This product contains Ponceau 4R (E124) red colouring which may cause allergic reactions.
This medicinal product contains less than 1 mmol sodium (23 mg) per 10 ml dose, that is to say essentially 'sodium-free'.
This medicinal product contains 2003.5 mg propylene glycol in each 10 ml dose. While propylene glycol has not been shown to cause reproductive or developmental toxicity in animals or humans, it may reach the foetus and was found in milk. As a consequence, administration of propylene glycol to pregnant or lactating patients should be considered on a case by case basis. Medical monitoring is required in patients with impaired renal or hepatic functions because various adverse events attributed to propylene glycol have been reported such as renal dysfunction (acute tubular necrosis), acute renal failure and liver dysfunction.
This medicinal product contains macrogol glycerol hydroxystearate 40. It may cause stomach upset and diarrhoea.
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-hydroxyindoleacetic acid 5-HIAA) and vanillylmandelic acid (VMA).
Expectorants such as guaifenesin should not be combined with cough suppressants in the treatment of cough since the combination is illogical and patients may be exposed to unnecessary adverse effects.
No interaction studies have been performed which revealed an interaction with guaifenesin.
Pregnancy
There are no or limited amount of data from the use of guaifenesin in pregnant women. Animal studies are insufficient with respect to reproductive toxicity (see section 5.3). Benylin Mucus Cough Max Menthol Flavour 100 mg/5 ml Oral Solution is not recommended during pregnancy and in women of childbearing potential not using contraception.
Breast-feeding
Guaifenesin is excreted in breast milk in small amounts. There is insufficient information on the effects of guaifenesin in newborns/infants. A decision must be made whether to discontinue breast-feeding or to discontinue/abstain from Benylin Mucus Cough Max Menthol flavour 100 mg/5 ml Oral Solution therapy, taking into account the benefit of breast feeding for the child and the benefit of therapy for the woman.Fertility
There is insufficient information available to determine whether guaifenesin has the potential to impair fertility.Guaifenesin has no or negligible influence on the ability to drive and use machines.
Summary of the safety profile
Anaphylaxis has been reported. The undesirable effects have been reported spontaneously during post-marketing use. Due to limited clinical trial data, a frequency cannot be estimated from the available data and is therefore classified as “not known”.'
The following side effects may be associated with the use of guaifenesin:
| SOC | Frequency Category | Adverse Event Term |
| Immune System Disorders | Not Known | Hypersensitivity reactions including pruritus and urticaria Rash Anaphylactic reaction |
| Gastrointestinal Disorders | Not Known | Gastrointestinal discomfort, nausea, vomiting |
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: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
Symptoms and signs
The symptoms and signs of overdose may include gastro-intestinal discomfort, nausea and drowsiness.
When taken in excess, guaifenesin may cause renal calculi.
Management
Treatment should be symptomatic and supportive.
Pharmacotherapeutic Group: Cough and Cold Preparations, Expectorants, ATC Code: R05CA03
Mechanism of action
This product is thought to exert its pharmacological action by stimulating receptors in the gastric mucosa. This increases the output from secretory glands of the gastrointestinal system and reflexly increases the flow of fluids from glands lining the respiratory tract. The result is an increase in volume and decrease in viscosity of bronchial secretions. Other actions may include stimulating vagal nerve endings in bronchial secretory glands and stimulating certain centres in the brain, which in turn enhance respiratory fluid flow. Guaifenesin produces its expectorant action within 24 hours.
There is no information available on the pharmacokinetics of guaifenesin in special populations.
Absorption
Guaifenesin is well absorbed from the gastro-intestinal tract following oral administration, although limited information is available on its pharmacokinetics. After the administration of 600 mg guaifenesin to healthy adult volunteers, the Cmax was approximately 1.4 ug/ml, with tmax occurring approximately 15 minutes after drug administration.
Distribution
No information is available on the distribution of guaifenesin in humans.
Biotransformation and elimination
Guaifenesin appears to undergo both oxidation and demethylation. The drug is rapidly metabolized in the liver via oxidation to β-(2-methoxyphenoxy)-lactic acid. The demethylation of GGE (hydroxyguaifenesin) is performed by O-demethylase, localized in liver microsomes. Following an oral dose of 600 mg guaifenesin to 3 healthy male volunteers, the t½ was approximately 1 hour and the drug was not detectable in the blood after approximately 8 hours.
Guaifenesin is excreted predominantly in the urine. Approximately 40% of a dose is excreted as the metabolite beta-2-methoxyphenoxy-lactic acid in the urine within 3 hours. Following oral dosing of 400 mg guaifenesin, more than 60% of a dose is hydrolysed within 7 hours, with no parent drug detectable in the urine.
Carcinogenicity
There is insufficient information available to determine whether guaifenesin has carcinogenic potential.
Mutagenicity
There is insufficient information available to determine whether guaifenesin has mutagenic potential.
Teratogenicity
There is insufficient information available to determine whether guaifenesin has teratogenic potential.
Fertility
There is insufficient information available to determine whether guaifenesin has the potential to impair fertility.
Xanthan gum
Sodium chloride
Saccharin sodium
Ammonium glycyrrhizate
Sodium benzoate (E211)
Citric acid
Sodium citrate
Macrogol glycerol hydroxystearate 40
Levomenthol
Raspberry flavour F2126 (includes ethanol)
Caramel (E150)
Ponceau 4R (E124)
Glycerol
Macrogol 1500
Propylene glycol (E1520)
Ethanol 96%
Purified water
Not applicable.
3 years
In-use: 4 weeks
Do not store above 25°C
Store in the original container to protect from light
Type III, Amber glass bottle, containing 150 ml, fitted with:
A plastic child resistant cap fitted with a PET-faced wad.
No special requirements.
Any unused medicinal product should be disposed of in accordance with local requirements.
McNeil Products Limited
1 Station Hill Square
Station Hill
Reading
RG1 1LN
UK
PL 15513/0165
5 May 2010 / 02 Aug 2018
22 September 2026
1 Station Hill Square, Station Hill, Reading, RG1 1LN
00800 555 22000