Hooking you with a core truth: what you eat this winter can quietly alter how well your medicines work, so festive indulgence isn’t off-limits—it just needs a plan. And this is the part that many people miss: thoughtful choices now can prevent surprises later in the season. Here's a clear, beginner-friendly rewrite of the MHRA guidance, expanded where helpful to deepen understanding while preserving all key points.
As the festive period approaches, many of us enjoy dishes and drinks that aren’t part of our everyday routine. The Medicines and Healthcare products Regulatory Agency (MHRA) reminds everyone that some seasonal favorites — such as traditional Christmas vegetables, extra sugary treats, and certain cheeses — can interact with medicines. These interactions may change how well a medicine works or raise the chance of side effects.
During the holidays, eating and drinking habits often shift. It’s important to recognize how these changes can influence your treatment. Certain foods, drinks, and supplements can either lessen a medicine’s effectiveness or increase the likelihood of adverse effects.
A well-known example involves warfarin, a medicine commonly used to prevent or treat blood clots:
Cranberry products, including juices and sauces, may heighten the risk of bruising or bleeding for people taking warfarin.
Leafy greens and brassica vegetables — such as Brussels sprouts, broccoli, and cabbage — are high in vitamin K, which can reduce warfarin’s effectiveness when consumed in large or inconsistent amounts. (Some supplements may also contain vitamin K, so it’s important to read labels carefully.)
There’s no need to avoid these foods entirely. The MHRA recommends that anyone taking warfarin keep their intake of vitamin K-rich foods consistent, especially during the festive period when diets often change.
Festive treats can also influence how other medicines behave. For individuals using insulin, sugary seasonal snacks — including chocolates and sweets — can lead to unexpected fluctuations in blood glucose levels. Enjoy these foods in moderation and follow the guidance provided by your healthcare team to stay well during the holidays.
Some traditional festive dishes can interact with specific medicines. Tyamine-rich foods like aged cheeses, cured meats, and dark chocolate can pose problems for people taking certain medicines such as monoamine oxidase (MAO) inhibitors (a class of antidepressants). If you’re on one of these medications, review the information that accompanies your prescription and adhere to any advised food restrictions.
Dr. Stephanie Millican from MHRA’s Safety and Surveillance team notes:
Many people don’t realize that what we eat and drink can affect how some medicines work. With a little planning and the right guidance, you can enjoy your festive favorites while keeping your treatment on track.
The safest approach is to read the Patient Information Leaflet (PIL) that accompanies your medicine and to ask your pharmacist or GP if you’re unsure about potential interactions. Healthcare professionals can offer personalized advice to ensure your treatment remains safe and effective throughout the festive season.
If you experience unexpected side effects or have concerns about a medicine, you can report them via the Yellow Card scheme at https://yellowcard.mhra.gov.uk/. Reporting helps the MHRA monitor product safety and protect others from harm.
Notes for editors
The Medicines and Healthcare products Regulatory Agency (MHRA) regulates all medicines and medical devices in the UK, ensuring they work as intended and are acceptably safe. All work is grounded in robust, evidence-based judgments to ensure that benefits justify any risks.
The MHRA is an executive agency of the Department of Health and Social Care.
For media inquiries, contact newscentre@mhra.gov.uk or call 020 3080 7651.
