Prescription medication · Thyroid Hormone (T3)
liothyronine
Also sold as Cytomel. This medicine treats hypothyroidism, a condition where your thyroid gland doesn't make enough thyroid hormone.
Data updated 2026-05-15
- 8,408
- FDA reportsLightly reported
- 17
- InteractionsSeveral interactions
- 47% less
- Generic vs brandReal savings
- $0.51
- Brand price (NADAC)
What the data shows
liothyronine (Cytomel) is a prescription Thyroid Hormone (T3), reported less often than most tracked drugs (8,408 FDA reports), with a lower-cost generic available (47% less than brand).
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
liothyronine (Cytomel) is a prescription Thyroid Hormone (T3). This medicine treats hypothyroidism, a condition where your thyroid gland doesn't make enough thyroid hormone.
Liothyronine (Cytomel) is a medicine that replaces a thyroid hormone called T3. It helps your body work properly if you don't make enough thyroid hormone on your own.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Brand Price
$0.51/unit
Generic Price
$0.27/unit
Generic Savings
47%
Generic Available
Yes (7 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine treats hypothyroidism, a condition where your thyroid gland doesn't make enough thyroid hormone.
Common side effects
Fatigue, Increased appetite, Weight loss
Key warnings
This medicine should not be used for weight loss or to treat obesity.
The sections below are summarized in plain English from liothyronine's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Liothyronine is a synthetic form of the T3 thyroid hormone. It works by increasing thyroid hormone levels in your body. This helps to regulate your body's metabolism and energy levels.
Side Effects (from patient reports)
Based on 8,408 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for liothyronine, by number of reports
- Headache
Headache
859 reports
- Fatigue
Fatigue
816 reports
- Nausea
Nausea
569 reports
- Dyspnoea
Dyspnoea
549 reports
- Pain
Pain
469 reports
- Hypertension
Hypertension
461 reports
- Malaise
Malaise
431 reports
- Weight Increased
Weight Increased
431 reports
- Hypothyroidism
Hypothyroidism
426 reports
- Feeling Abnormal
Feeling Abnormal
411 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for liothyronine each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where liothyronine sits
liothyronine has more FDA adverse-event reports than 35% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is liothyronine; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 8,408 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
8,408
Reports Mentioning Death
195
2.3% of reports — not proof of cause
Hospitalization Reports
1,457
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 2 | HEADACHE | 859 |
| 3 | FATIGUE | 816 |
| 4 | NAUSEA | 569 |
| 5 | DYSPNOEA | 549 |
| 6 | PAIN | 469 |
| 7 | HYPERTENSION | 461 |
| 8 | MALAISE | 431 |
| 9 | WEIGHT INCREASED | 431 |
| 10 | HYPOTHYROIDISM | 426 |
| 11 | FEELING ABNORMAL | 411 |
| 12 | DIZZINESS | 385 |
| 13 | DIARRHOEA | 374 |
| 15 | ASTHMA | 354 |
| 16 | INSOMNIA | 351 |
| 17 | GASTROOESOPHAGEAL REFLUX DISEASE | 350 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
This medicine should not be used for weight loss or to treat obesity. Taking high doses of thyroid hormone for weight loss can cause serious and life-threatening side effects, especially when taken with stimulant medicines.
Known Drug Interactions
Other drugs: Amiodarone Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients.
Mechanism: This interaction can stop your body from turning one type of thyroid hormone into another, which can change your blood test results.
Administration of sertraline in patients stabilized on liothyronine sodium tablets may result in increased liothyronine sodium tablets requirements.
Mechanism: This antidepressant can lower the effectiveness of your thyroid medicine, meaning your body might need a higher dose.
Other drugs: Carbamazepine Furosemide (>80 mg IV) Heparin Hydantoins Non-Steroidal Anti-inflammatory Drugs - Fenamates These drugs may cause protein binding site displacement. Furosemide has been shown to inhibit the protein binding of T4 to TBG and albumin, causing an increased free-T4 fraction in serum. Furosemide competes for T4-binding sites on TBG, prealbumin, and albumin, so that a single high dose can acutely lower the total T4 level.
Mechanism: This water pill can knock thyroid hormones off the proteins they usually ride on in your blood, which changes the amount of active hormone in your body.
Drug or Drug Class Effect Beta-adrenergic antagonists (e.g., Propranolol >160 mg/day) In patients treated with large doses of propranolol (>160 mg/day), T3 and T4 levels change, TSH levels remain normal, and patients are clinically euthyroid.
Mechanism: Taking high doses of this blood pressure medicine can change the amount of thyroid hormones found in your blood.
7.5 Antidepressant Therapy Concurrent use of tricyclic (e.g., amitriptyline) or tetracyclic (e.g., maprotiline) antidepressants and liothyronine sodium tablets may increase the therapeutic and toxic effects of both drugs, possibly due to increased receptor sensitivity to catecholamines.
Mechanism: Using these two drugs together can make both of them more powerful and increase the risk of side effects.
This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.
Common Questions
Can I use this medicine for weight loss?
What should I do if I experience chest pain?
How often will my doctor check my thyroid levels?
Can this medicine affect my blood sugar if I have diabetes?
What are the symptoms of taking too much of this medicine?
Can I take this medicine with other medications?
What if I have heart disease?
Can this medicine cause bone loss?
Is it safe to take this medicine during breastfeeding?
What happens if I stop taking this medicine?
What are the common side effects of liothyronine?
Does liothyronine interact with other medications?
What drug class is liothyronine?
Is there a generic version of liothyronine?
What pregnancy or breastfeeding source fields are listed for liothyronine?
Related Medications in Thyroid Hormone (T3)
Other drugs grouped near liothyronine - same-class peers and common alternatives.
levothyroxine
Synthroid, Levoxyl
Levothyroxine is a medicine that replaces a hormone normally made by your thyroid gland.
Compare with liothyronine →
methimazole
Tapazole
Methimazole (Tapazole) is a medicine that lowers the amount of thyroid hormone your body makes.
Compare with liothyronine →
propylthiouracil
PTU
Propylthiouracil (PTU) is a medicine that treats an overactive thyroid.
Compare with liothyronine →
thyroid (desiccated)
Armour Thyroid, Nature-Throid
Armour Thyroid is a natural thyroid hormone medicine.
Compare with liothyronine →
Compare beyond drug class
Nationwide peers by FAERS volume & death-report share
Two PlainMeds-derived comparison paths for liothyronine: nearest FDA FAERS report volume and nearest death-report share among drugs with at least 1,000 logged reports, excluding same-class neighbors listed above. Counts reflect reporting volume, not proven individual harm.
Similar FAERS report volume
Nearest drugs by total FAERS reports. This record: 8,408.
Similar death-report share
Nearest drugs by FAERS death-report share. This record: 2.32%.
- canagliflozin Δ 0.03 pts · 29,554 reports · SGLT2 Inhibitor 2.29%death share
- sumatriptan Δ 0.03 pts · 36,885 reports · Triptan (Serotonin 5-HT1 Agonist) 2.35%death share
- progesterone Δ 0.05 pts · 21,004 reports · Progestogen Hormone 2.27%death share
- cenobamate Δ 0.10 pts · 6,460 reports · Anticonvulsant 2.41%death share
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
FDA bioequivalence and label-record context for narrow therapeutic index medicines
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for liothyronine
The FDA label for liothyronine (sold under brand names such as Cytomel) classifies it as a prescription-only medication in the Thyroid Hormone (T3) class. This medicine treats hypothyroidism, a condition where your thyroid gland doesn't make enough thyroid hormone. Official labeling lists 18 commonly reported side effects, including Fatigue, Increased appetite, Weight loss.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 8,408 voluntary reports. The database also lists 17 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.27 versus $0.51 for the brand - a 47% generic savings.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.
Last updated: March 15, 2024
PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages