Can treating my thyroid mean I do not need a statin?

Sometimes. If hypothyroidism was the main cause, LDL can fall a lot once thyroid levels are normal. If your LDL was high before the thyroid problem, or your heart risk is high, you may still need a statin. Your clinician decides with a repeat lipid panel.

Is it safe to take a statin and levothyroxine together?

Yes, many people take both. The statin label warning is about uncontrolled hypothyroidism, which raises the risk of muscle problems. Tell your clinician about any new muscle pain or weakness.

Does hypothyroidism raise triglycerides too?

It can. The 2026 ACC/AHA dyslipidemia guideline lists uncontrolled hypothyroidism as a secondary cause of high triglycerides. In a 2020 meta-analysis, levothyroxine did not clearly lower triglycerides in overt hypothyroidism, so the main effect is on total and LDL cholesterol.

Can an overactive thyroid cause low cholesterol?

Yes. Hyperthyroidism is linked to low total and LDL cholesterol. In the 2020 meta-analysis, treatment of overt hyperthyroidism raised total cholesterol by about 45 mg/dL and LDL by about 31 mg/dL.

Will my HDL cholesterol change on levothyroxine?

It may fall slightly. In overt hypothyroidism, HDL fell by about 4 mg/dL on average with treatment. That change is small next to the fall in LDL.

Can Hypothyroidism Cause High Cholesterol, and Does Levothyroxine Lower It?

The short answer: Yes. An underactive thyroid raises total and LDL cholesterol, mainly because the liver removes less LDL from the blood. Levothyroxine lowers it again. In a 2020 meta-analysis, treatment of overt hypothyroidism lowered LDL cholesterol by about 41 mg/dL and total cholesterol by about 58 mg/dL. In subclinical hypothyroidism the effect is much smaller.

That is why a thyroid test belongs in the workup of high cholesterol. A cholesterol problem caused by the thyroid can improve when the thyroid is treated.

Why does hypothyroidism raise cholesterol?

Your liver clears LDL cholesterol from the blood through LDL receptors on its surface. Thyroid hormone tells liver cells to make those receptors. When thyroid hormone is low, the liver makes fewer of them, and LDL stays in the blood longer.

A 2018 review in Frontiers in Endocrinology states that high cholesterol in hypothyroidism is mainly due to reduced LDL receptor activity. The same review reports two more effects:

Fewer receptors: LDL receptor messenger RNA falls by nearly 50% in hypothyroidism.
Less cholesterol leaves in bile: Bile acid flow slows, and the liver secretes less cholesterol into bile.

Triglycerides can rise too. HDL cholesterol is usually normal, or even high in severe hypothyroidism, according to an earlier review in Thyroid. The typical pattern is high total cholesterol and high LDL.

That review also notes that hypothyroidism often comes with diastolic high blood pressure, which adds to the load on the arteries. Our sibling site hypertension.md covers blood pressure in detail.

How often is the thyroid behind high cholesterol?

More often than many people expect. The 2018 review reports that 1.4% to 13% of patients with high lipids have hypothyroidism. It cites one cohort of 8,795 patients in which TSH was high in 5.2% of those diagnosed with hyperlipidemia.

The effect is graded. Lipid levels rise as thyroid function falls. People with a TSH between 5.1 and 10 mIU/L already have higher average total and LDL cholesterol than people with normal thyroid function, the review states.

Most high cholesterol still has other causes: genes, diet, weight, diabetes, and kidney or liver disease. A thyroid cause is the exception. It is worth finding because the treatment is different.

How much does levothyroxine lower cholesterol in overt hypothyroidism?

Overt hypothyroidism means TSH is high and free T4 is low. Here the effect of treatment is large. A 2020 systematic review and meta-analysis in the Journal of Clinical Endocrinology and Metabolism pooled randomized and observational studies. Levothyroxine therapy in overt hypothyroidism was linked to these average changes:

Total cholesterol: down 58.4 mg/dL
LDL cholesterol: down 41.1 mg/dL
Apolipoprotein B: down about 34 mg/dL
HDL cholesterol: down 4.1 mg/dL
Triglycerides: no statistically clear change

These are averages. The authors note that the studies varied in patient mix, severity of thyroid disease, and length of follow-up. Your own result depends on how low your thyroid hormone was and on what your cholesterol was before the thyroid failed.

Levothyroxine corrects only the thyroid part of the problem. If your LDL was high before you became hypothyroid, it will probably still be high after treatment. Our levothyroxine guide explains how the medicine is dosed and adjusted.

Does it help in subclinical hypothyroidism?

A little. Subclinical hypothyroidism means TSH is high and free T4 is still normal. A 2017 meta-analysis of 12 randomized trials with 940 participants found that levothyroxine lowered:

Total cholesterol by 0.29 mmol/L (about 11 mg/dL)
LDL cholesterol by 0.22 mmol/L (about 9 mg/dL)

It found no significant effect on HDL cholesterol or triglycerides. The effect was similar in trials that enrolled only people with a TSH below 10 mIU/L. It was weaker in trials longer than 6 months than in shorter trials.

A 2022 meta-analysis in adults 60 and older also found lower total and LDL cholesterol on levothyroxine. It found no significant effect on fatigue, hypothyroid symptoms, or quality of life.

A 9 mg/dL fall in LDL is small. These trials measured cholesterol numbers. They did not show fewer heart attacks or strokes. High cholesterol alone is not a settled reason to treat a mildly raised TSH. The 2012 American Thyroid Association and AACE guideline says the decision to treat when TSH is below 10 mIU/L should be tailored to the individual patient.

Should your thyroid be checked before you start a statin?

There are two reasons to check. The first is the diagnosis. The 2026 ACC/AHA guideline on the management of dyslipidemia lists hypothyroidism among the secondary causes of high LDL cholesterol. For adults with an LDL of 190 mg/dL or higher, it gives a class 1 recommendation: exclude and address secondary causes of dyslipidemia. The guideline also lists uncontrolled hypothyroidism as a cause of high triglycerides.

The second reason is muscle safety. The FDA label for atorvastatin (Lipitor) states that risk factors for myopathy include "age 65 years or greater, uncontrolled hypothyroidism, renal impairment," certain other drugs, and higher statin doses. Myopathy is muscle pain, tenderness, or weakness with a raised creatine kinase level. The 2026 guideline also lists hypothyroidism among the factors linked to statin muscle symptoms.

The check is a single blood test for TSH. Our guide to thyroid blood tests explains the result. Treating the thyroid does not rule out a statin. Many people need both, and the 2018 review notes that thyroid hormone may add to the effect of statins in people with both conditions.

When is cholesterol rechecked after you start levothyroxine?

None of the sources we reviewed gives a fixed interval for the lipid recheck. The thyroid timeline is clear. The levothyroxine (Synthroid) label says to monitor TSH 6 to 8 weeks after any change in dose. Once the dose is stable, it says to check every 6 to 12 months.

A cholesterol result is easier to read after your TSH is back in range. A lipid panel taken while you are still hypothyroid shows the thyroid effect and your baseline together. Ask your clinician when to repeat the panel.

If you already take a statin and get new muscle pain, weakness, or dark urine, call your clinician. Do not stop or start either medicine on your own.

The bottom line

Hypothyroidism can cause high cholesterol, and it is a cause that treatment can reverse. In overt hypothyroidism, levothyroxine lowers LDL by about 41 mg/dL on average. In subclinical hypothyroidism the fall is about 9 mg/dL, a small change. If your LDL is high, ask if your TSH has been checked. This matters most before you start a statin, because uncontrolled hypothyroidism raises the risk of statin muscle problems.

Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Talk with your clinician before you start, stop, or change levothyroxine or any cholesterol medicine.