Synthroid vs Addyi: side-by-side comparison
Synthroid (Hormones and Birth Control) and Addyi (Women's Sexual Health) belong to different therapeutic classes and are rarely interchangeable. This page compares the medications' purposes, mechanisms and the situations where each is used.
| Property | Synthroid | Addyi |
|---|---|---|
| Active ingredient | Levothyroxine | Flibanserin |
| Manufacturer | AbbVie | Sprout Pharmaceuticals |
| Class | Hormones and Birth Control | Women's Sexual Health |
| Strengths | 25mcg, 50mcg, 75mcg, 100mcg, 150mcg | 100mg |
| Forms | tablet | tablet |
What's the same
Synthroid and Addyi 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
Synthroid belongs to Hormones and Birth Control while Addyi belongs to Women's Sexual Health. 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
Synthroid: Levothyroxine replaces deficient endogenous thyroxine, which is converted in tissues to the active hormone triiodothyronine (T3) by deiodinase enzymes. Addyi: Sexual desire is modulated by complex central nervous system pathways involving serotonin (generally inhibitory) and dopamine and norepinephrine (generally excitatory).
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.
When Addyi is preferred
Addyi is indicated for the treatment of acquired, generalised hypoactive sexual desire disorder (HSDD) in premenopausal women.
Frequently asked questions
Is Synthroid or Addyi better? ▾
Synthroid and Addyi 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 Synthroid to Addyi? ▾
Switching between Synthroid and Addyi 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 Synthroid and Addyi 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 Synthroid comparisons
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.