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Prescribing Information for Liquid Medicines

Dose Prescribing Information for Liquid Medicines

The dose of the medicine on a prescription must be expressed in terms that are explicit.


Single active ingredient

The form of the medication must be stated for controlled drug preparations e.g. oral liquid, suspension, elixir etc. It is good practice to state the form routinely.

Liquid medicines will be supplied clearly labelled with the amount of active ingredient specified in milligrams etc. per unit volume (the strength) e.g. 5mg in 5ml. The strength must appear on the prescription for controlled drugs. The strength must be stated where more than one strength of a preparation exists. It is good practice to state the strength of the medicine routinely.

In the case of liquid preparations, the dose should be expressed as milligrams or micrograms of the active ingredient, i.e. in the units of mass not the volume.

It is quite straightforward for healthcare professionals to calculate the volume to be given from the prescription if written as above.

[facsimile prescription BNF 64 p 5].


Multi-ingredient preparations

Non-proprietary names of compound preparations which appear in the BNF may be used. Prescribers must not create their own compound names for the purposes of generic prescribing as they have no approved definition and can be misinterpreted.

Dose in millilitres should only be used for multi-ingredient preparations where the abbreviation ‘ml’ may be used.

Where more than one strength combination of a multi-ingredient preparation exists, both strength and dose to be administered must be stated e.g. Co-Amoxiclav suspension 250/62 in 5ml, 5ml dose.

(Serious medication errors have arisen from confusion between milligrams and micrograms when the latter units have been abbreviated. The abbreviation ‘mg’ for milligram may be used. Doses of less than one milligram must be expressed in micrograms e.g. 62.5micrograms, not 0.0625mg. The word microgram must be written in full – ‘mcg’ and’μg’ are not acceptable.)


Labelling of Oral Liquid Preparations

Limited health literacy is a common problem and a medicine safety issue. Evidence supports the use of numeric rather than alphabetic characters for numbers.

Each dose from a multi-dose container is administered by means of a device suitable for measuring the prescribed dose by volume. The device is usually a spoon or a measuring cup for volumes of 5 ml or multiples thereof, or an oral syringe for other volumes or, for Oral drops, a suitable dropper. Dosage instructions for patients should be expressed on prescription medicine labels in terms of volume (ml).

Dosage, usage and administration instructions must clearly separate dose from interval and must provide the explicit frequency of drug administration  e.g., " Take 10ml in the morning and 10ml in the evening" is better than "Take 10ml by mouth twice daily".


Appleby, GE & Wingfield J. 2009. Dale and Applebe’s Pharmacy law and ethics. 9th ed. London; Pharmaceutical Press.

British Medical Association & Royal Pharmaceutical Society. 2012 BNF No 64. London. BMJ group & Royal Pharmaceutical Society of Great Britain.

Davis, TC., Federman, AD., Bass, PF., Jackson, RH., Middlebrooks, M. Parker, RM. and Wolf, MS.  2009. Improving patient understanding of prescription drug label instructions. J Gen Intern Med.24(1), pp. 57–62. Available at: [Accessed: 5th Nov 2012].

Disabled World News. 2010. Promoting establishment of universal standards for prescription medication labels. Available at [Accessed: 5th Nov 2012].

The Institute for Safe Medication Practices. 2012. principles of designing a medication label for oral liquids for patient specific directions for in-patient use.

Available at: [Accessed: 5th Nov 2012].

The International Pharmacopoeia Fourth Edition. Monographs; Dosage forms; general Monographs; Liquids for Oral Use. Available at: [Accessed: 5th Nov 2012].


A. MacRobbie 5th Nov 2012 on behalf of SPCPA