Prescribed medical cannabis oil and a CBD product sold as a food are not the same thing. A prescription identifies a specific medicine, strength and set of directions for one patient. A shop-bought product does not replace it, even if both labels mention cannabis or CBD.
Key takeaways
- The pharmacy label and prescription, not a product nickname or online description, are the instructions that apply to you.
- Strength may be written as a concentration, such as milligrams per millilitre. Check the units as well as the number.
- Use only the measuring device and route stated in the supplied instructions.
- Tell the prescriber or pharmacist about medicines, supplements and retail CBD products you use because interactions are possible.
- Do not change the amount, timing, product or food routine without asking the clinical team how the directions apply.
- Keep the oil in its labelled container, store it exactly as instructed and never share it.
Prescription oil and retail CBD
The NHS describes medical cannabis as a prescription medicine. Many cannabis-based products for medicinal use are unlicensed medicines, which means they have not received a UK marketing authorisation for that specific product and use. The GMC places additional responsibility on a specialist prescriber who decides that an unlicensed CBPM is clinically appropriate.
CBD oils sold as foods or supplements sit in a different system. Food Standards Agency advice applies to CBD food products, not prescribed medicines. Retail availability is not evidence that a product has the same composition, quality controls or clinical purpose as the item on a prescription. A retail product also cannot be used as proof of lawful possession of a prescribed controlled medicine.
If you use both, tell the clinical team. The NHS warns that CBD and THC can affect how other medicines work, including through liver-enzyme effects. A pharmacist or prescriber needs the actual product names and strengths to assess that risk.
Reading the dispensing label
Read the label each time a new bottle arrives. It should identify the patient and medicine and give the directions supplied by the pharmacy. The carton, bottle or accompanying information may also state:
- THC and CBD strength, with the unit used
- total volume and batch details
- the route of administration and measuring device
- storage, expiry and after-opening instructions
- pharmacy and prescriber contact details.
Do not compare two oils by the largest number on the label alone. A concentration, a total amount in the bottle and an amount per measured dose describe different things. If the units or directions are unclear, pause and ask the dispensing pharmacy rather than estimating with a household spoon or remembered number.
Use the supplied measuring device if one is provided. Do not copy another patient’s routine or alter how the oil is taken because of advice from a forum. Food, timing and missed-dose instructions can be product-specific; follow the label and ask the pharmacy if your routine makes that difficult.
The broader guide to how prescribed medical cannabis may be supplied explains other forms. Medical cannabis oil versus flower gives a neutral set of questions for a consultation, and what to ask if you are prescribed medical cannabis oil is a practical handover checklist.
Storage, travel and side effects
Follow the storage wording on that bottle. Different products can have different temperature, light and after-opening requirements. Keep the labelled container away from children and anyone for whom it was not prescribed. Do not decant it into an unlabelled travel bottle.
Before travel, check the current rules for every country on the journey. GOV.UK advises carrying controlled medicine in its original packaging with proof that it was prescribed, such as a prescriber letter containing the required details. Destination and transit-country rules may differ from UK rules.
Possible effects listed by the NHS include tiredness, dizziness, feeling high, mood or behavioural changes, hallucinations and suicidal thoughts. Contact the clinical team about side effects, a dispensing discrepancy or an unexpected response. Seek urgent help for a severe or immediately dangerous reaction. Do not drive or operate machinery if impaired; a prescription is not a declaration that you are fit to drive at a particular time.
Speak to the prescriber or pharmacist before making changes if you are pregnant, planning pregnancy or breastfeeding; take other regular medicines; have liver, heart or mental-health concerns; or need advice about driving, safety-critical work or travel.
Read next
- What to ask if you are prescribed medical cannabis oil
- CBD versus THC in a prescription context
- Medical cannabis oil versus flower
- Licensed cannabis medicines in the UK
Source trail
- NHS: Medical cannabis, side effects and interactions
- NHS England: Cannabis-based products for medicinal use (CBPMs)
- GMC: Information for doctors on cannabis-based products for medicinal use
- MHRA: Supply of unlicensed medicinal products
- Food Standards Agency: Consumer advice on CBD foods
- GOV.UK: Take medicine in or out of the UK
