Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Rifampin may increase the amount of levothyroxine in your body.
What might happen:
Your medication may have an increased effect on your body. Signs and symptoms to look for include: weight loss, rapid heartbeat, nervousness, sweating, tremor, fatigue, and difficulty sleeping.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Goldberg AS, Tirona RG, Asher LJ, Kim RB, Van Uum SH. Ciprofloxacin and rifampin have opposite effects on levothyroxine absorption. Thyroid 2013 Nov;23(11):1374-8.
2.Isley WL. Effect of rifampin therapy on thyroid function tests in a hypothyroid patient on replacement L-thyroxine. Ann Intern Med 1987 Oct; 107(4):517-8.
3.Nolan SR, Self TH, Norwood JM. Interaction between rifampin and levothyroxine. South Med J 1999 May;92(5):529-31.