heparin vs levothyroxine
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Side-by-side comparison of heparin and levothyroxine. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
minor Known Drug Interaction
Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement. Other drugs: Carbamazepine Furosemide (> 80 mg IV) Heparin Hydantoins Non-Steroidal Anti-inflammatory Drugs - Fenamates These drugs may cause protein-binding site displacement.
Heparin Sodium
Synthroid, Levoxyl, Tirosint
Heparin is a medicine that helps prevent and treat blood clots. It is given as an injection into a vein or under the skin.
Levothyroxine is a medicine that replaces a hormone normally made by your thyroid gland. It is used when the thyroid doesn't make enough hormone on its own.
Heparin is used to prevent and treat blood clots in your veins and lungs. It can also prevent clots after surgery or if you have an irregular heartbeat called atrial fibrillation. Heparin can also treat blood clotting problems throughout your body and prevent clots during surgery, blood transfusions, or dialysis.
This medicine treats hypothyroidism, a condition where the thyroid gland doesn't make enough thyroid hormone. It can be used in adults and children, even newborns. Levothyroxine can also be used after surgery and radioiodine therapy for thyroid cancer to help lower thyroid-stimulating hormone (TSH) levels.
Heparin works by stopping certain proteins in your blood from forming clots. It helps to thin your blood and prevent new clots from forming. It does not dissolve existing blood clots, but it can keep them from getting bigger.
Levothyroxine provides a synthetic form of thyroxine (T4), which is the main hormone produced by the thyroid gland. Your body converts T4 into triiodothyronine (T3), the active form of the hormone. By providing T4, levothyroxine helps restore normal thyroid hormone levels in your body.
- • Bleeding
- • Irritation at the injection site
- • Allergic reactions
- • Increased liver enzyme levels
- • Fatigue
- • Increased appetite
- • Weight loss
- • Feeling hot
- • Headache
- Heparin-Induced Thrombocytopenia 1,207
- Nausea 708
- Drug Hypersensitivity 603
- Vomiting 572
- Hypotension 547
- Fatigue 25,847
- Nausea 22,026
- Headache 18,797
- Diarrhoea 18,176
- Dyspnoea 16,216
Heparin can cause serious bleeding, which can be fatal. It can also cause a severe reaction called heparin-induced thrombocytopenia (HIT), where your body attacks your own platelets. Make sure your doctor knows if you have ever had HIT. Using the wrong strength of heparin can also cause fatal bleeding.
Thyroid hormones, including levothyroxine, should not be used for weight loss or to treat obesity. Using high doses can cause serious and life-threatening side effects, especially when taken with stimulant medicines.
If you are pregnant, talk to your doctor about the risks and benefits of using heparin. Preservative-free heparin is recommended during pregnancy if available. It is not known if heparin passes into breast milk, so it is recommended to avoid breastfeeding while using this medicine.
Tell your doctor if you are pregnant or plan to become pregnant. Your levothyroxine dose may need to be adjusted during pregnancy. Levothyroxine passes into breast milk, but it is not expected to harm the baby.
How to Read This heparin vs levothyroxine Comparison
heparin is classified in the Unfractionated Heparin drug class, while levothyroxine sits within the Thyroid Hormone class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, heparin has 3,637 submissions while levothyroxine has 101,062. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known minor interaction flagged in FDA labeling, attributed to heparin can push the thyroid medicine off the proteins it normally hitches a ride on in your blood.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for heparin or levothyroxine.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.