Can You Take Lansoprazole with Levothyroxine?
Last reviewed: · Source: US FDA drug label database
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Like all PPIs, lansoprazole can reduce levothyroxine absorption over time — separate the doses and recheck thyroid levels after starting or stopping the PPI.
Not sure this applies to your situation? Check your levels at HealthLabs.com — no GP referral needed →
- Long-term lansoprazole use can reduce how well levothyroxine is absorbed, by lowering stomach acid, just like other PPIs.
- Take levothyroxine on an empty stomach, ideally at least 30-60 minutes before food, drink, or other medicines.
- Have your thyroid levels rechecked around 6-8 weeks after starting or stopping lansoprazole, as your levothyroxine dose may need adjusting.
- This isn't a reason to avoid either medication — it's a reason to monitor thyroid levels a bit more closely.
Is it safe to take Lansoprazole with Levothyroxine?
Levothyroxine absorption depends partly on stomach acid, which lansoprazole suppresses. The result can be a gradual rise in TSH and a return of hypothyroid symptoms despite an unchanged levothyroxine dose. The drugs can absolutely be used together — just take levothyroxine correctly (empty stomach, 30-60 minutes before breakfast), take lansoprazole before a different meal, and have TSH rechecked about 6-8 weeks after any PPI change.
How do Lansoprazole and Levothyroxine interact?
PPI-induced hypochlorhydria impairs levothyroxine tablet dissolution and absorption. Studies show increased levothyroxine dose requirements in long-term PPI users. Liquid/soft-gel levothyroxine formulations are less pH-dependent and are an option where the interaction proves troublesome.
Data sourced from the US Food and Drug Administration (FDA) drug label database: OpenFDA levothyroxine label — gastric acidity and absorption.
Interaction severity
Rated minor: like all PPIs, lansoprazole reduces stomach acid needed for full levothyroxine absorption, which can gradually reduce its effectiveness with long-term use — a manageable, monitorable effect rather than a dangerous interaction.
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Anyone with previously stable thyroid function that drifts after starting lansoprazole, pregnant women on levothyroxine, and people already needing high or fluctuating levothyroxine doses.
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What if I've already taken Lansoprazole and Levothyroxine?
No urgency — this is a slow absorption effect. Optimise dose timing as above and book a TSH test 6-8 weeks after the PPI change. Report returning tiredness, weight gain, or cold intolerance.
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Not sure if this combination is safe for your specific situation?
HealthLabs.com lets you check liver enzyme or kidney function levels before combining medications long-term — no GP referral needed.
Check your levels at HealthLabs →Always speak to your pharmacist or GP for personalised medical advice. Affiliate link — we may earn a commission.
Frequently Asked Questions
Can I take lansoprazole with levothyroxine?
Yes, with sensible timing — levothyroxine on an empty stomach before breakfast, lansoprazole before another meal — and a TSH recheck after starting the PPI.
How far apart should the doses be?
Levothyroxine 30-60 minutes before breakfast; lansoprazole works well 30 minutes before the evening meal. Total separation isn't the issue — consistent routine and monitoring are.
My thyroid symptoms came back after starting lansoprazole — why?
Reduced stomach acid can lower levothyroxine absorption. A TSH test will confirm; your GP can raise the dose or switch formulation.
Do antacids cause the same problem?
Calcium/magnesium/aluminium antacids directly bind levothyroxine — separate those by at least 4 hours. The PPI effect is slower and via acid suppression.