Synthroid vs Aygestin: side-by-side comparison
Synthroid (Hormones et contraception) and Aygestin (Santé sexuelle féminine) 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 | Aygestin |
|---|---|---|
| Active ingredient | Levothyroxine | Norethindrone |
| Manufacturer | AbbVie | Various generics |
| Class | Hormones et contraception | Santé sexuelle féminine |
| Strengths | 25mcg, 50mcg, 75mcg, 100mcg, 150mcg | 5mg |
| Forms | tablet | tablet |
What's the same
Synthroid and Aygestin 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 et contraception while Aygestin belongs to Santé sexuelle féminine. 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: La lévothyroxine remplace la thyroxine endogène déficitaire, convertie dans les tissus en hormone active, la triiodothyronine (T3), par les enzymes désiodases. Aygestin: La noréthistérone se lie aux récepteurs de la progestérone et exerce des effets progestatifs : épaississement de la glaire cervicale, suppression du pic de LH, amincissement de l'endomètre et réduction de l'activité des…
When Synthroid is preferred
Synthroid est autorisé dans l'hypothyroïdie de toute cause (thyroïdite de Hashimoto, post-thyroïdectomie, post-iode radioactif, congénitale), dans le goitre et dans la freination de la TSH après cancer thyroïdien différencié.
When Aygestin is preferred
Aygestin est autorisé dans les douleurs associées à l'endométriose, les saignements utérins anormaux d'origine hormonale et l'aménorrhée secondaire.
Questions fréquentes
Is Synthroid or Aygestin better? ▾
Synthroid and Aygestin 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 Aygestin? ▾
Switching between Synthroid and Aygestin 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 Aygestin 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
Les informations publiées sur ce site sont fournies à titre documentaire et pédagogique. Elles ne remplacent pas l'avis d'un professionnel de santé qualifié.