From the FDA Drug Label
The risk of hypertension increases with concomitant administration of drugs that increase blood pressure (phenylephrine, pseudoephedrine, ephedrine, dihydroergotamine, thyroid hormones or droxidopa). Avoid concomitant use of drugs that increase blood pressure. If concomitant use cannot be avoided, monitor blood pressure closely
Midodrine and levothyroxine should be used together with caution, as levothyroxine is a thyroid hormone that can increase blood pressure, and midodrine can also increase blood pressure. Close monitoring of blood pressure is recommended if these two drugs are used concomitantly 1.
From the Research
Midodrine and levothyroxine can generally be taken together, but it is crucial to separate these medications by at least 2-4 hours to minimize potential interactions, as suggested by the most recent study on medication interactions 2. When considering the concomitant use of midodrine and levothyroxine, several factors must be taken into account to ensure the safe and effective management of orthostatic hypotension and hypothyroidism.
- Levothyroxine should be taken on an empty stomach, typically first thing in the morning, 30-60 minutes before food, to maximize its absorption.
- Midodrine is usually taken three times daily (upon waking, midday, and late afternoon, but not after 6 PM) to avoid nighttime hypertension while lying down. The main concern with taking these medications close together is that midodrine may potentially affect the absorption of levothyroxine, although there is limited direct evidence on this specific interaction 2. Additionally, both medications can affect heart rate and blood pressure - midodrine increases blood pressure (its therapeutic purpose for orthostatic hypotension), while levothyroxine can increase heart rate and cardiac output, as noted in studies on their individual effects 3, 4. Patients taking both medications should monitor for symptoms like excessive heart palpitations, significant blood pressure changes, or unusual dizziness, and regular follow-up with healthcare providers is important to ensure appropriate dosing and to monitor thyroid function tests and blood pressure, in line with recommendations for managing orthostatic hypotension and hypothyroidism 5, 6.