Can I take Levothyroxine and Vitamin b12 together?
Drug interaction guide
Originally published 25 Jan 2026
Meets Patient’s editorial guidelines
- DownloadDownload
- Share
- Language
- Discussion
There is no known direct interaction between levothyroxine and vitamin B12. They do not interfere with how each other works in the body, nor do they change how each other is absorbed or broken down.
In this article:
Continue reading below
Why this happens
Levothyroxine is a synthetic thyroid hormone absorbed in the small intestine, while vitamin B12 (cobalamin) is absorbed further down in the ileum with the help of 'intrinsic factor'. They use different pathways for metabolism and excretion.
What you should do
You can safely take both levothyroxine and vitamin B12. However, for the best results, levothyroxine should be taken on an empty stomach, 30 to 60 minutes before breakfast. Vitamin B12 can be taken at the same time or later in the day with food. If your B12 supplement is part of a multivitamin containing calcium or iron, you must wait at least 4 hours after taking your levothyroxine before taking the supplement, as calcium and iron can block thyroid hormone absorption.
Continue reading below
Using other medicines
Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.
Disclaimer
This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.
Patient picks for Drug interactions

Treatment and medication
Can I take Maitake and Shiitake together?
Taking maitake and shiitake mushrooms together may increase the risk of bruising or bleeding. Both mushrooms contain natural compounds that can thin the blood and slow down the clotting process. While they are commonly eaten together in food, taking them in concentrated supplement form increases this effect.

Treatment and medication
Can I take Cordyceps and Lions mane together?
There are no known negative interactions between Cordyceps and Lion's Mane mushrooms. In fact, they are frequently taken together in 'mushroom blends' because they work in different ways. Cordyceps is typically used for energy and physical stamina, while Lion's Mane is used for brain health and focus. Taking them together may provide a combined benefit for both physical and mental performance.
Continue reading below
Article history
The information on this page is written and peer reviewed by qualified clinicians.
25 Jan 2026 | Originally published

Ask, share, connect.
Browse discussions, ask questions, and share experiences across hundreds of health topics.

Feeling unwell?
Assess your symptoms online for free
Sign up to the Patient newsletter
Your weekly dose of clear, trustworthy health advice - written to help you feel informed, confident and in control.
By subscribing you accept our Privacy Policy. You can unsubscribe at any time. We never sell your data.