Levothyroxine (Synthroid) & Dry Eye: Is There a Connection?
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Hypothyroidism affects millions of adults, particularly women over 40, and levothyroxine (often known by the brand name Synthroid) is one of the most commonly prescribed hormone replacement medications in the world.
But many thyroid patients also report dry, irritated, or gritty eyes — and they want to know: Is it the medication? The thyroid? Something else entirely?
In this blog, we’ll take a closer look at the connection between levothyroxine, thyroid disease, and dry eye, and what patients and eye doctors should know when symptoms show up.
The link between hypothyroidism and dry eye disease
Hypothyroidism slows down many bodily functions — including the glands responsible for producing tears and the oily layer that keeps those tears from evaporating too quickly.
Several studies show people with thyroid dysfunction frequently experience:
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Reduced tear production
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Higher tear evaporation
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Meibomian gland dysfunction (MGD)
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Chronic irritation, burning, or “tired eyes”
Even before a patient begins levothyroxine, the underlying condition may already be causing ocular surface symptoms.
Autoimmune thyroid disease increases risk
A large percentage of hypothyroid patients have Hashimoto’s thyroiditis, an autoimmune condition. Autoimmune activity can directly affect:
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The lacrimal glands (tear production)
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The meibomian glands (oil production for the tear film)
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The eyelids, increasing inflammation, redness, and crusting
Patients often report:
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Grittiness
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Light sensitivity
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Burning
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Styes or frequent blepharitis flare-ups
For these patients, dry eye isn’t just a nuisance — it’s part of the systemic inflammatory picture.
Levothyroxine adjustments may temporarily worsen dryness
While levothyroxine is not typically the cause of dry eye, starting or adjusting the dosage can temporarily shift hormone levels. When that happens, patients may notice:
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Sudden changes in tear film stability
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Brief worsening of dryness or irritation
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Increased sensitivity to wind, screens, or contact lenses
This phase is usually temporary and stabilizes as the body adapts to the new dose.
Contact lens wearers may feel the impact more
Thyroid-related dryness can make contact lens wear less comfortable. The tear film destabilizes more easily, leading to:
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A gritty sensation
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Reduced all-day wear time
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Increased lens awareness
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More lens-related irritation
For symptomatic contact lens users, this can be the first noticeable sign of thyroid imbalance or medication shifts.
What patients can do: Practical management tips
Thyroid-related dry eye is manageable — and patients do best when they combine optimized thyroid care with consistent eye care habits. Recommended strategies include:
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Daily eyelid cleansing to reduce debris, mites, and inflammation
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Warm compresses to support meibomian gland function
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Omega-3 or fish oil support, when appropriate
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Humidifier use, especially during winter or in dry climates
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Artificial tears or doctor-recommended drops for lubrication
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Regular thyroid labs to ensure levothyroxine dosage is optimized
Patients often experience meaningful improvement with consistent eyelid hygiene alone, especially when MGD is playing a role.
When to call your doctor
Patients should seek additional evaluation if they notice:
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Worsening dryness after a dose change
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New eye swelling or pressure
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Unexplained vision changes
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Persistent eye pain or redness
These may indicate the medication dose needs adjusting — or that another ocular condition is present.
Conclusion
Levothyroxine itself is rarely the root cause of dry eye — but the condition it treats, hypothyroidism, is strongly associated with ocular dryness, MGD, and tear instability.
Autoimmune thyroid disease adds another layer of risk, and medication adjustments can temporarily intensify symptoms.
The good news? With consistent eyelid care, optimized thyroid levels, and appropriate dry eye management, most patients experience significant relief.