Formoterol and Phentermine interaction
Formoterol and Phentermine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Formoterol (FORMOTEROL FUMARATE) label · effective 2020-12-15
The increased risk of asthma-related death is considered a class effect of the long-acting beta 2 -adrenergic agonists, including formoterol fumarate inhalation solution.
Clinically significant cardiovascular effects and fatalities have been reported in association with excessive use of inhaled sympathomimetic drugs.
• Use with caution in patients with cardiovascular or convulsive disorders, thyrotoxicosis, or with sensitivity to sympathomimetic drugs.
• Use of long-acting beta 2 -adrenergic agonists (LABA) as monotherapy [without inhaled corticosteroids (ICS)] for asthma is associated with an increased risk of asthma-related death.
Therefore, formoterol fumarate inhalation solution, like other sympathomimetic amines, should be used with caution in patients with cardiovascular disorders, especially coronary insufficiency, cardiac arrhythmias, and hypertension.
From the Phentermine (Phentermine hydrochloride) label · effective 2026-08-17
…states • History of drug abuse • Pregnancy [ see Use in Specific Populations () ] • Nursing [ see Use in Specific Populations ( 8.3 ) ] • Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines • History of cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension) () • During or within…
• Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines ( 4 )
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.