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Synephrine

Synephrine

Best for

Use more fat for energy

Barely detectable 3–60 mg/kg/day 1 meta-analysis, n=377 #6 of 21 studied

Synephrine lacks enough research to establish meaningful reductions in body fat or weight, while limited findings on energy use remain too small and early for confident conclusions.

Median effective dose, most-studied outcomes

  • Support basic functions at rest 50 mg —
Full protocol, 5 outcomes

Risk, worst reported severity

  • myocardial infarction severe
  • stroke (cerebral infarction/vasospasm) severe
  • isoprenaline major
  • ephedrine major
All 18 events and interactions

What synephrine actually does

Outcome Effect Evidence Dose Time Rank
Early research 4
Lose body fat Not enough research Body fat loss changes the proportion of your body that is fat tissue.
small 		1 meta-analysis 1 papers · n=94 10–54 mg — —
Use more fat for energy Barely detectable Fat burning means your body uses stored or circulating fat as a source of energy.
trivial 		1 meta-analysis 2 papers · n=377 3–60 mg/kg — #6 /21
Lose weight Not enough research Weight loss means carrying less total body weight over time.
trivial 		1 meta-analysis 1 papers · n=94 10–54 mg — —
Raise resting metabolic rate Not enough research Resting metabolic rate is the energy your body uses while you are at rest.
— 		1 RCT 1 papers · n=— 50 mg — —

Effect tiers come from native-unit MCID where available, Cohen's d otherwise.

Protocol

Dose, timing & forms

How much

Weight and body-fat trials used 10 to 54 mg daily, but they did not show significant reductions in either outcome.1 One small study found higher resting energy use with 50 mg, while exercise research tested roughly 3 mg/kg and found only a trivial shift toward fat use as fuel.12 These protocols describe research exposure, not a proven dose for weight loss.

When and how long

The limited acute research assessed synephrine around activity or as a single exposure, rather than showing that a particular daily schedule produces lasting weight change.12 Taking it before exercise does not turn the small fuel-use shift into demonstrated fat loss.2 Given its stimulant-like cardiovascular activity, avoid treating it as an occasional energy booster, and do not combine it with caffeine or other stimulants without clinical guidance.1

Forms & standardisation

Most human research identifies the active compound as p-synephrine, while real-world products often use bitter orange extract.12 Choose neither based on a vague “bitter orange” front label alone: an extract can vary in p-synephrine content and include other compounds. More importantly, better label detail does not solve the lack of meaningful weight-loss evidence or the cardiovascular safety concern.1

Studied range, by outcome

Outcome Studied range Median effective Duration Evidence
Lower body fat percentage 10–54 mg — — 1 paper
Move toward a healthier weight 10–54 mg — — 1 paper
Use more fat as fuel 3 mg/kg — — 1 paper
Support basic functions at rest 50 mg 50 mg — 1 paper 1 sig. endpoint
Reduce total body fat 10–54 mg — — 1 paper

Adverse events and drug interactions

Safety events

myocardial infarction severe
stroke (cerebral infarction/vasospasm) severe
rhabdomyolysis severe
acute coronary syndrome severe
cardiac arrhythmia severe
stroke severe
seizure severe
QT prolongation severe

Drug interactions

other major additive
isoprenaline major additive
ephedrine major increases toxicity
caffeine moderate decreases concentration
dapsone moderate decreases concentration
nebivolol moderate decreases effect
caffeine moderate increases effect
gliclazide moderate increases effect
chlorzoxazone minor unknown
metformin minor unknown
Buy well

Recommended Synephrine products

Real products that dose Synephrine where the research does, in a clean formulation, from brands we've audited. We only list ones we'd stand behind.

Chosen for adequate Synephrine dosing vs. the studied range, a clean formulation (grade A–C), and independent brand-quality audits. Not sponsored.

In context

What this is and how it works

  • Across 1 study (n=94), body-fat and weight outcomes showed no reliable direction; a noticeable-change threshold was unavailable.1
  • Six papers reviewed here span 35 outcomes, with all evidence classified as early.
  • Safety concerns matter especially for people with cardiovascular risks or concurrent stimulant use.1

Synephrine is a natural compound found in bitter orange, also called Citrus aurantium. Supplement labels often market bitter orange extract or p-synephrine for energy, appetite, exercise, and weight management, even though an extract can contain more than synephrine alone.1

Synephrine activates parts of the body's adrenaline signaling network, which can nudge heart activity and energy use upward.1 Think of it like turning up a thermostat that controls both the furnace and some of the house wiring: more output is possible, but the system you are pushing also affects cardiovascular strain.1 In a small exercise study, p-synephrine shifted fuel use toward fat, but that shift was too small to establish meaningful fat loss.2

Bottom line

Skip synephrine if your goal is meaningful weight or body-fat loss. The small, early findings on energy use and exercise fuel selection do not outweigh the absence of convincing body-composition results.12 Anyone with cardiovascular concerns, or anyone using caffeine, ephedrine, or other stimulants, should avoid it unless a qualified clinician specifically advises otherwise.13

Frequently asked

Common questions

Does synephrine help you lose weight?

Not based on the available human evidence. Trials using 10 to 54 mg did not show meaningful weight or body-fat reductions, and the observed weight effect was trivial.1

Does synephrine burn fat during exercise?

A small exercise study found a shift toward using more fat for fuel, but the practical size of that change was trivial. It did not establish body-fat loss over time.2

Is synephrine safer than other stimulants?

Do not assume it is harmless because it comes from bitter orange. Synephrine stimulates adrenaline-related signaling, and serious cardiovascular events have been reported with stimulant-containing supplements, especially combination products.13

Can you take synephrine with caffeine?

Avoid stacking synephrine with caffeine or other stimulants unless a qualified clinician tells you otherwise. Combining compounds that push the cardiovascular system can increase risk, while existing trials do not show a worthwhile weight-loss payoff.1

Sources

Sources

  1. 1. Safety, efficacy, and regulatory status of Citrus aurantium extract and p-synephrine (2010) ↑
  2. 2. Acute effects of p-synephrine on fat oxidation during exercise in humans (2016) ↑
  3. 3. Adverse cardiovascular and central nervous system events associated with dietary supplements containing ephedra alkaloids (2001) ↑

Generated August 27, 2026

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