Levothyroxine
Brand: Synthroid, Levoxyl
Boxed warning
Not for obesity or weight loss: large doses can cause serious or life-threatening toxicity, especially with sympathomimetic amines.
- Caution
- Contraindicated in untreated adrenal insufficiency; overtreatment causes palpitations, bone loss, and atrial fibrillation.
- Storage
- Room temperature, protected from light and moisture.
- Pregnancy
- Continue in pregnancy: dose requirements often increase and are rechecked each trimester.
Common side effects
- Rapid heartbeat
- Nervousness
- Insomnia
- Weight loss
- Tremor
Key interactions
- Separate from calcium and iron by 4 hours
- Antacids reduce absorption
- Take away from certain foods and fiber
- Affects warfarin blood thinner
Counseling points
- Take on an empty stomach in the morning
- Wait 30-60 minutes before eating
- Take at the same time each day
- Do not switch brands without approval
- Report chest pain or palpitations
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