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T3 Liothyronine - Active Thyroid Hormone

The most active form of thyroid hormone that directly regulates metabolism, energy production, and cellular function throughout the body

Scientific nameLiothyronine sodium (T3) FormulaC15H12I3NO4 Molecular weight650.97 g/mol CAS6893-02-3
95 absorption score
3 safety / 10
200 USD per month
5 documented interactions

Check it against something

Evidence level A

T3 Liothyronine - Active Thyroid Hormone with:

Compatibility score 82 out of 100
82 out of 100
Works better together Compatible. Timing differs, so follow each supplement's own window.

Check it against your whole stack →

What it does

mechanism and evidence for each claim

Dramatically increased metabolic rate and energy

Significantly boosts metabolism, thermogenesis, and overall energy levels

Direct activation of cellular metabolism and mitochondrial function Evidence A-grade 1-3 days

Enhanced fat burning and weight management

Accelerates lipolysis and promotes efficient fat metabolism

Increases metabolic rate and thermogenic activity Evidence A-grade 1-2 weeks

Improved cognitive function and mental clarity

Enhances brain metabolism, focus, and mental processing speed

Optimizes brain energy metabolism and neurotransmitter function Evidence A-grade 3-7 days

Enhanced physical performance and recovery

Improves exercise capacity, strength, and recovery from training

Increases cellular energy production and protein synthesis Evidence B-grade 1-3 weeks

Better mood and emotional stability

Supports mood regulation and reduces depression symptoms

Optimizes neurotransmitter production and brain energy metabolism Evidence A-grade 1-4 weeks

Others take these for the same thing

Same goal, different mechanism — check any of them against this one

Melatonin Sleep support & circadian rhythm 0.5-3mg A 50% Ashwagandha Stress management & energy 300-600mg A 75% Vitamin B12 (Cyanocobalamin) Energy & nerve support 250-1000 mcg A 70% Coenzyme Q10 (CoQ10) Heart health & cellular energy 100-200mg A 10% Phosphorus Bone health & energy metabolism 700-1250mg A 80% Vitamin B3 (Niacinamide) Energy & skin health (no flush) 100-1000 mg A 88%

Every pair we checked

12 combinations scored by the engine
T3 Liothyronine - Active Thyroid Hormone + Calcium Carbonate Significantly reduces T3 absorption when taken together Needs attention 58
T3 Liothyronine - Active Thyroid Hormone + Caffeine No documented interaction either way No known interaction 70
T3 Liothyronine - Active Thyroid Hormone + Creatine Monohydrate No documented interaction either way No known interaction 70
T3 Liothyronine - Active Thyroid Hormone + Vitamin D3 No documented interaction either way No known interaction 70
T3 Liothyronine - Active Thyroid Hormone + Whey Protein No documented interaction either way No known interaction 70
T3 Liothyronine - Active Thyroid Hormone + Lactase No documented interaction either way No known interaction 70
T3 Liothyronine - Active Thyroid Hormone + Bovine Collagen No documented interaction either way No known interaction 70
T3 Liothyronine - Active Thyroid Hormone + DHA No documented interaction either way No known interaction 70
T3 Liothyronine - Active Thyroid Hormone + Turmeric No documented interaction either way No known interaction 70
T3 Liothyronine - Active Thyroid Hormone + L-Tyrosine Supports thyroid hormone production Works better together 78
T3 Liothyronine - Active Thyroid Hormone + Selenium (Thyroid Support) Enhanced T4 to T3 conversion and thyroid function Works better together 82
T3 Liothyronine - Active Thyroid Hormone + Iodine (Thyroid Support) Essential for thyroid hormone synthesis Works better together 82

Dosage

Morning empty stomach
DailyPRESCRIPTION ONLY - 5-50mcg
Replacement therapyMEDICAL SUPERVISION - 12.5-25mcg daily
Optimization therapyMEDICAL SUPERVISION - 25-50mcg daily
Advanced protocolsMEDICAL SUPERVISION - individualized dosing
MaximumNEVER exceed 100mcg daily without intensive medical monitoring

When to expect it

First Effects6-12 hours for initial metabolic and energy effects
Peak Benefits1-2 weeks for optimal metabolic enhancement and energy
Deficiency DevelopmentT3 deficiency develops with hypothyroid conditions
Toxicity OnsetCan occur within hours of overdose - requires immediate medical attention

How to measure it

$150-300
MarkerFree T3, Total T3, Reverse T3, TSH, Free T4, cardiac markers
OptimalFree T3: 3.0-4.2 pg/mL, Total T3: 80-200 ng/dL
Deficient belowFree T3 < 2.3 pg/mL
FrequencyWeekly initially, then monthly during dose optimization

What actually reaches you

The label counts the carrier, your body does not
Absorption Very high 95 of 100 · best absorbed form of this compound
Delivered daily 0 mg
Cost per 100 mcg delivered $25.52 comparative — uses the absorption score, not a measured percentage

Works better with

3 documented
+
Selenium

Enhanced T4 to T3 conversion and thyroid function

Selenium is essential for deiodinase enzyme function · level A
+
Iodine

Essential for thyroid hormone synthesis

Iodine is the core component of thyroid hormones · level A
+
Tyrosine

Supports thyroid hormone production

Tyrosine is the amino acid backbone of thyroid hormones · level B

What not to take with T3 Liothyronine - Active Thyroid Hormone

2 documented
!
Soy Products

May interfere with thyroid hormone absorption and function

Soy isoflavones can affect thyroid hormone metabolism · moderate significance
!
Calcium Iron Supplements

Significantly reduces T3 absorption when taken together

Mineral interference with intestinal absorption · high significance

Medication interactions

Discuss these with a pharmacist before combining
warfarin-blood-thinners Severe

T3 enhances anticoagulant effects

What to do: Requires frequent INR monitoring and dose adjustments

diabetes-medications Moderate

T3 increases insulin requirements

What to do: Monitor blood glucose closely and adjust medications

heart-medications Severe

May alter cardiovascular drug effects

What to do: Careful cardiac monitoring required

Available forms

bioavailability compared
Liothyronine Sodium (T3) 95

Liothyronine Sodium (T3): Most potent thyroid hormone, Fast-acting, Direct metabolic effects, Bypasses T4 conversion issues

Food sources

before you supplement
NO natural food sources of T3 T3 must be synthesized by the body or taken as medication · N/A
Thyroid glandular supplements Variable T3 content, not standardized · 60
Prescription liothyronine Precise pharmaceutical dosing 5-100mcg · 95

Too little

deficiency signs
  • T3 deficiency symptoms (hypothyroidism):
  • Severe fatigue and low energy
  • Significant weight gain and slow metabolism
  • Cold intolerance and low body temperature
  • Depression and cognitive fog
  • Constipation and digestive issues
  • Dry skin, hair loss, and brittle nails

Too much

toxicity signs
  • T3 excess symptoms (hyperthyroidism) - MEDICAL EMERGENCY:
  • Rapid or irregular heart rate
  • Chest pain and shortness of breath
  • Excessive sweating and hyperthermia
  • Severe anxiety and agitation
  • Tremors and muscle weakness
  • Nausea, vomiting, and diarrhea

Who benefits most

hypothyroid-t4-conversion-issues

Direct T3 supplementation bypasses T4 to T3 conversion problems

MEDICAL SUPERVISION REQUIRED - typically 5-25mcg daily
severe-hypothyroid-symptoms

More potent and faster-acting than T4 for severe cases

PRESCRIPTION ONLY - individualized medical dosing
thyroid-hormone-resistance

Higher potency may overcome receptor resistance

SPECIALIZED MEDICAL CARE - higher doses under monitoring
advanced-thyroid-optimization

Precise metabolic control for experienced users

MEDICAL SUPERVISION - typically 12.5-50mcg daily
competitive-athletes-metabolic-enhancement

Enhanced fat loss and performance (DANGEROUS without supervision)

NOT RECOMMENDED - high risk of serious side effects

Where to buy it

compare forms first

Look for T3 Liothyronine - Active Thyroid Hormone at PRESCRIPTION ONLY - 5-50mcg per serving. The form that matters here is Liothyronine Sodium (T3).

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What else affects it

Beyond other supplements
!
Soy products

May interfere with thyroid hormone absorption and function

Soy isoflavones can affect thyroid hormone metabolism

How it works

  • Directly binds to nuclear thyroid hormone receptors (TR-alpha and TR-beta)
  • Increases mitochondrial oxygen consumption and ATP production
  • Enhances protein synthesis and cellular growth
  • Stimulates thermogenesis and heat production
  • Regulates carbohydrate and lipid metabolism
  • Modulates cardiovascular function and heart rate

Key findings

what the evidence supports
  • T3 is the most active form of thyroid hormone with potent metabolic effects
  • More effective than T4 for certain thyroid conditions and conversion issues
  • Requires careful medical supervision due to narrow therapeutic window
  • Can cause serious cardiac and metabolic complications if misused

Sources: NIH Examine.com · data reviewed 2026-08-01

Compiled by Denis, who maintains this database and holds no medical qualification — every figure here is sourced or derived, never asserted. How we calculate it →

Common questions

What are the benefits of T3 Liothyronine - Active Thyroid Hormone?

Documented effects: Dramatically increased metabolic rate and energy; Enhanced fat burning and weight management; Improved cognitive function and mental clarity; Enhanced physical performance and recovery. Significantly boosts metabolism, thermogenesis, and overall energy levels

How much T3 Liothyronine - Active Thyroid Hormone should you take per day?

The common daily range is PRESCRIPTION ONLY - 5-50mcg. By goal — replacement therapy: MEDICAL SUPERVISION - 12.5-25mcg daily; optimization therapy: MEDICAL SUPERVISION - 25-50mcg daily; advanced protocols: MEDICAL SUPERVISION - individualized dosing; maximum: NEVER exceed 100mcg daily without intensive medical monitoring.

When is the best time to take T3 Liothyronine - Active Thyroid Hormone?

Morning empty stomach. First effects are typically reported within 6-12 hours for initial metabolic and energy effects.

What are the side effects of T3 Liothyronine - Active Thyroid Hormone?

At excessive doses: T3 excess symptoms (hyperthyroidism) - MEDICAL EMERGENCY:, Rapid or irregular heart rate, Chest pain and shortness of breath, Excessive sweating and hyperthermia, Severe anxiety and agitation. Safety rating at normal doses is 3 out of 10.

What should you not take with T3 Liothyronine - Active Thyroid Hormone?

Separate it from Soy Products, Calcium Iron Supplements by two to four hours. May interfere with thyroid hormone absorption and function

Does T3 Liothyronine - Active Thyroid Hormone interact with medications?

Documented interactions with warfarin-blood-thinners, diabetes-medications, heart-medications. Discuss these with a pharmacist before combining.

How do you know if you need T3 Liothyronine - Active Thyroid Hormone?

The marker is Free T3, Total T3, Reverse T3, TSH, Free T4, cardiac markers, optimal range Free T3: 3.0-4.2 pg/mL, Total T3: 80-200 ng/dL. Common deficiency signs: T3 deficiency symptoms (hypothyroidism):, Severe fatigue and low energy, Significant weight gain and slow metabolism, Cold intolerance and low body temperature.

Taken for

62 Energy & Metabolism

Vitamin B12 (Methylcobalamin) · Ashwagandha · Vitamin B12 (Cyanocobalamin)

 27 Hormones

Melatonin · Vitamin B6 (Pyridoxine HCl) · Vitamin B6 (P5P)