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Can I take Levothyroxine and Simvastatin together?

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Taking these two medicines together is generally safe, but levothyroxine can affect how well simvastatin works. If your thyroid levels are not properly controlled (hypothyroidism), simvastatin may be less effective at lowering your cholesterol, and you may be at a slightly higher risk of muscle-related side effects from the statin.

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Varför detta händer

Thyroid hormones influence how the body processes cholesterol and how it metabolises statin medications. An underactive thyroid can lead to higher levels of fats in the blood and may slow down the breakdown of simvastatin in the body.

You can take these medicines together, but ensure your doctor monitors your thyroid stimulating hormone (TSH) levels regularly. If your levothyroxine dose is changed, your doctor may also want to check your cholesterol levels or monitor you for any new muscle aches or pains.

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Heart conditions (e.g. angina, heart failure)

If you have a heart condition, your dose must be started very low and increased slowly. Contact your doctor immediately if you experience chest pain or palpitations, as levothyroxine increases the workload on your heart.

Graviditet

You must not take simvastatin if you are pregnant or planning to become pregnant, as it may harm the developing baby. Use effective contraception while taking this medicine.

Muscle disorders (Myopathy/Rhabdomyolysis) - simvastatin

You must report any unexplained muscle pain, tenderness, or weakness to your doctor immediately. This is especially important if you also feel unwell or have a fever, as it can lead to serious kidney damage.

Grapefruit and Grapefruit Juice

You must avoid eating grapefruit or drinking grapefruit juice while taking simvastatin. Grapefruit contains compounds that increase the level of simvastatin in your blood, which significantly increases your risk of serious side effects, such as muscle damage (rhabdomyolysis).

Interaction with supplements (Calcium/Iron)

Do not take calcium tablets, iron supplements, or multivitamins at the same time as levothyroxine. You must leave a gap of at least 4 hours between these supplements and your levothyroxine to ensure the medicine works.

Diabetes

Levothyroxine can raise blood sugar levels. If you have diabetes, you must monitor your blood glucose more closely when starting or changing your dose, as your diabetes medication may need to be increased.

Alkohol

It is best to avoid or strictly limit alcohol while taking levothyroxine. While there is no direct chemical reaction, alcohol can affect thyroid function and may worsen symptoms like tiredness or mood changes.

It is best to avoid or strictly limit alcohol when taking simvastatin. Both alcohol and simvastatin can affect your liver; combining them increases the risk of liver damage and may also increase the risk of muscle side effects.

Timing of dose and food/drink

Take your levothyroxine on an empty stomach, at least 30 to 60 minutes before breakfast or any caffeine. Food, milk, and coffee prevent the medicine from being absorbed properly.

Caffeine (Coffee/Tea)

Caffeine can significantly reduce the amount of levothyroxine your body absorbs. You should wait at least 30 to 60 minutes after taking your tablet before drinking coffee or tea.

Dairy products (Milk, Yoghurt, Cheese)

Avoid consuming dairy products at the same time as your levothyroxine. Calcium found in dairy can interfere with how your body absorbs the medicine, making it less effective. It is best to wait at least 4 hours between taking levothyroxine and consuming dairy.

Soya products

Soya can interfere with the absorption of levothyroxine. If you regularly eat or drink soya products, your doctor may need to monitor your thyroid levels more closely. Avoid consuming soya at the same time as your dose.

Kelp and Seaweed

These foods are naturally high in iodine. Too much iodine can interfere with your thyroid treatment and make your condition worse.

High-fibre foods

A diet very high in fibre can reduce the absorption of levothyroxine. If you significantly change your fibre intake, inform your doctor as your dose may need adjusting.

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Taking multiple medicines? Our Interaktionskontroll för läkemedel helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Ansvarsfriskrivning

Denna information är endast avsedd för allmän utbildning och bör inte användas som en ersättning för professionell medicinsk rådgivning. Rådfråga alltid din läkare, apotekare eller annan kvalificerad vårdpersonal innan du fattar beslut om dina mediciner. Individuella omständigheter kan variera, och endast en vårdpersonal som känner till din medicinska historia kan ge personlig vägledning.

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Artikelhistorik

Informationen på denna sida är skriven och granskad av kvalificerade kliniker.

  • 25 jan 2026 | Ursprungligen publicerad
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