Symbicort vs Synthroid: side-by-side comparison
Symbicort (Respiratory Medications) and Synthroid (Hormones and Birth Control) belong to different therapeutic classes and are rarely interchangeable. This page compares the medications' purposes, mechanisms and the situations where each is used.
| Property | Symbicort | Synthroid |
|---|---|---|
| Active ingredient | Budesonide, Formoterol | Levothyroxine |
| Manufacturer | AstraZeneca | AbbVie |
| Class | Respiratory Medications | Hormones and Birth Control |
| Strengths | 80/4.5 mcg, 160/4.5 mcg, 200/6 mcg, 400/12 mcg | 25mcg, 50mcg, 75mcg, 100mcg, 150mcg |
| Forms | dry powder inhaler, metered-dose inhaler | tablet |
What's the same
Symbicort and Synthroid are used in very different patients, and the points in common are limited. The main shared element is that both meet regulatory standards for efficacy and safety and benefit from pharmacist oversight.
Key differences
Symbicort belongs to Respiratory Medications while Synthroid belongs to Hormones and Birth Control. Indications, mechanisms and target populations differ. The comparison is most useful when a clinician has mentioned both medications and the patient wants to understand where each fits.
Mechanism and action
Symbicort: Budesonide reduces chronic airway inflammation through glucocorticoid receptor activation, decreasing inflammatory cell recruitment and cytokine release. Synthroid: Levothyroxine replaces deficient endogenous thyroxine, which is converted in tissues to the active hormone triiodothyronine (T3) by deiodinase enzymes.
When Symbicort is preferred
Symbicort is approved in adults and adolescents from age 12 (younger in some markets) for the regular treatment of asthma when combination therapy of a long-acting beta-2 agonist and an inhaled corticosteroid is appropriate, and in some markets for symptom relief in COPD.
When Synthroid is preferred
Synthroid is approved for hypothyroidism of any cause (Hashimoto thyroiditis, post-thyroidectomy, post-radioiodine, congenital), goitre and TSH suppression after differentiated thyroid cancer.
Frequently asked questions
Is Symbicort or Synthroid better? ▾
Symbicort and Synthroid are not interchangeable — they treat different conditions. Asking which is "better" is meaningful only when a clinician has weighed both for the same specific clinical scenario.
Can I switch from Symbicort to Synthroid? ▾
Switching between Symbicort and Synthroid is rarely an appropriate decision since they belong to different classes and treat different conditions. The real question is usually whether the diagnosis calls for one medication or the other — which the prescriber resolves.
Do Symbicort and Synthroid have the same side effects? ▾
No — they belong to different classes and have distinct side-effect profiles. Each medication has its own prescribing information.
More Symbicort comparisons
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.