How to read prescription instructions and medication labels

What do prescription instructions actually tell you?

A qualified doctor or healthcare professional provides a prescription when dispensing medications to a patient. The prescription is essentially a set of instructions on how to take the medication correctly. It should include information such as the strength of the medication, the appropriate dose, and the frequency of administration. 

But the formatting of this information, which often includes unfamiliar abbreviations, can be confusing.

What do common prescription abbreviations mean?

Many prescription abbreviations may be included in your medication instructions. So, let’s have a look at the meaning of these abbreviations, from the intended frequency of administration to the correct time to take them.

Frequency abbreviations

Time of day instructions

 

Every X hours instructions

 

Timing versus frequency of administration

‘Every X hours’ differs from ‘x times daily’ instructions: For example, while QDS and Q6H are technically both instructions for taking medication three times per day, they vary in their flexibility. See the table below:

More Latin abbreviations you might still see

 

What do food and timing instructions mean?

When you are prescribed certain medications, you may be instructed to administer them at certain times in relation to your food intake. This may be before food, after food, or with food. 

But what do these instructions actually mean?

Food-related instructions

What do PRN and “as directed” actually mean?

• PRN (or ‘as required’) is a common instruction on prescriptions for medications that are not required to be taken on a regular basis. 

It is usually used for medications prescribed to treat short-term or intermittent conditions or symptoms, such as pain, anxiety, or constipation. This means the medication can be taken as symptoms present, within limits. 

While PRN medications may not need to be administered according to a strict dosing regimen, they should be taken according to protocol. For example, patients should be advised on minimum intervals between doses and maximum dosage to be taken in a 24-hour period. Importantly, PRN is different to Ad Lib (as desired), which is largely unused nowadays.

• “As directed” is another common instruction found on prescriptions. These medications should be taken strictly according to the specific instructions provided by the prescribing doctor. 

This instruction reminds the patient to follow personalised guidance, as opposed to general guidance provided on the medication label. This typically follows a personal consultation with your doctor, after which they will advise you on the specific dosage, frequency, and administration requirements of the medication. 

If in doubt about the correct way to take your medication, always contact the prescribing doctor, nurse, or pharmacist for clarification.

Related dosing terms

• PRN dose: The specific dose that is to be administered. This will typically be accompanied by a frequency and a maximum 24-hour allowance (e.g., 50 mg, every 4-6 hours as required; do not exceed 300 mg over 24 hours).

• Breakthrough dose: An additional, fast-acting dose of medicine used to provide short-term relief. For example, a breakthrough dose of pain medication (often an opioid) may be given to treat sudden flares of pain.

What is the difference between dose and dosage?

Dose structure terms

 

How do medical cannabis prescription labels differ?

Medical cannabis, also referred to as cannabis-based medicines or cannabis-based medicinal products, can be legally prescribed in the UK as a treatment option for a wide range of symptoms and conditions. Like all prescription medications, medical cannabis products should be prescribed with clear instructions regarding their administration and dosage.

Let’s have a look at some common terms you might see.

Common terms you may see on medical cannabis labels

• PRN - As mentioned earlier, pro re nata or PRN indicates that the medication should be administered as required (within prescribed limits).

For example, a Releaf-issued prescription for medical cannabis flower may state: Vape 0.1g to 0.3g when needed, up to a maximum of 1g daily. Do not smoke.

• Titration - The gradual adjustment of a medication dose. This may take place over a number of days, weeks, or even months until the optimum dose is achieved.

• Up titration - Slowly increasing the dose of a medication until the most effective dose is found. Cannabis-based medicines are typically initially administered at low doses and up-titrated.

• Down titration - Slowly decreasing the dose of a medication to find the minimum effective dose, or to safely stop a medication. Allows side effects and withdrawal symptoms to be monitored.

• Maximum daily dose - The maximum dose of cannabis-based medicines or ingredients (such as THC) that should be administered in a 24-hour period.

For example, a Releaf-issued prescription for medical cannabis oil may state: Take 0.1 ml orally twice a day. Increase by 0.1 - 0.2 ml every 1 - 3 days (up titration), to a maximum of 1ml twice a day (maximum daily dose). 

Additional instructions that your medical cannabis prescribing specialist may suggest

• As directed - Always pay close attention to the specific guidance provided by the prescribing doctor. These instructions will have been determined based on your specific circumstances.

• Start low, go slow (or similar wording) - It is often recommended that patients start with a low dose of cannabis-based medicines. This can be gradually increased (up-titrated) over time to find the most effective dose.

• Dose range (rather than fixed dose) - Also known as variable dosing, a “dose range” refers to a dose that can be adjusted based on factors such as body weight. For example, the prescribed dose may be “X mg per kg (body weight) per day”.

What mistakes do people commonly make with prescription instructions?

With so much to consider when taking prescription medications, particularly those that are new to you, it can be easy to make a mistake. Let’s take a look at some of the most common mistakes people make with prescription medications, and what to do if they should happen to you. 

When should you ask for help?

Administration errors are common, especially when starting a new treatment plan. Thankfully, these mistakes are usually not associated with significant harm, and it is possible to simply continue with your dosing regimen as normal. 

However, in some cases, it is important to ask for help from your prescribing doctor or another health care professional. You should speak to a doctor if:

• The wrong medication was administered

• Too much or too little medication was taken

• A medication was administered via the incorrect route 

• Side effects occur

Frequently asked questions

What does PRN mean on a prescription?

“PRN” on a prescription means the medication should be taken as required. This typically means within certain limits, such as a maximum dose at specific intervals throughout the day.

What does OD mean in medication instructions?

“OD” in medication instructions means that the medication should be taken once daily. The abbreviation comes from the Latin omne die or omne in die, which translates to “once a day”.

What does “as directed” mean on a prescription?

“As directed” on a prescription means that the medication should be taken strictly according to the prescribing physician’s instructions. These may differ from the general guidance on the label, based on the medical history of the patient and the specific aims of treatment.

Can I take medicine at different times each day?

Generally, no, you should not take your medication at significantly different times each day. However, a dosing window of 1-2 hours is generally considered safe. The flexibility of your dosing regimen can vary depending on a number of factors. Always follow the guidance provided by your doctor. 

What happens if I miss a dose?

If you miss a dose of your medication, take it as soon as you remember, unless it is almost time for your next dose. Missing a dose can reduce medication efficacy or cause side effects such as withdrawal symptoms. If you have any concerns, contact a health care professional for further advice.

Does “with food” really matter?

In short: Yes, you should follow instructions when advised to take medications “with food”. Some medications are most effective when administered alongside food or on an empty stomach. For example, some medicines are better absorbed when administered alongside dietary fats. In addition, food can help to protect against certain side effects, such as stomach irritation and nausea.

Conclusion: Understanding your prescription is part of your treatment

When starting a new treatment regimen, following the prescription instructions is as important as the medication itself. It is therefore important to ensure you understand precisely how you are supposed to take your medication. Your prescribing physician should clearly explain all of your dosing requirements, including any abbreviations on your prescription. But if you are ever unsure, don’t hesitate to ask for clarification. 

Medical cannabis products are prescription medications that require careful administration and monitoring. Our expert clinicians are always on hand to help with any questions or concerns related to your prescription and dosing regimen. 

Not a patient but interested in the potential of medical cannabis treatment? Why not complete our online medical cannabis eligibility checker? It’s completely free and can tell you in seconds whether you could be eligible for a consultation with one of our specialist clinicians.

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