Thyroid medications
Narrow therapeutic index
Hypothyroidism — replacing the hormone an underactive thyroid isn't making.
Supplies thyroid hormone directly, restoring normal metabolic signalling.
The 2 thyroid medications in the PTCB Top 200
| Generic | Brand | Common use |
|---|---|---|
| Levothyroxine | Synthroid | hypothyroidism |
| Thyroid | Armour Thyroid | hypothyroidism |
Tap any generic name for its full drug guide — brand↔generic, side effects, interactions and the exam tip.
What to know for the exam
- check_circleTaken on an empty stomach, usually 30 to 60 minutes before breakfast.
- check_circleSeparated by about four hours from calcium, iron and antacids.
- check_circleLevothyroxine has a narrow therapeutic index — small dose changes matter.
- check_circleBlood levels are rechecked after any dose change.
Patients are generally kept on the same manufacturer. Switching products can shift blood levels enough to matter.
Levothyroxine is a standard example of a narrow-therapeutic-index drug.
Drill thyroid medications the way the PTCE asks them
RxReflex groups the Top 200 drugs into classes like this one, then quizzes you on brand↔generic, class, side effects and interactions. Plus a guided Learn path, pharmacy math and 40+ cheat sheets. Free to start.
Frequently asked
What drugs are in the thyroid medications class? add
Levothyroxine, Thyroid. All are in the PTCB Top 200.
What are thyroid medications used for? add
Hypothyroidism — replacing the hormone an underactive thyroid isn't making.
How do thyroid medications work? add
Supplies thyroid hormone directly, restoring normal metabolic signalling.
Last reviewed August 7, 2026. For education only — not medical advice. Not affiliated with or endorsed by the PTCB.