Synephrine C
No benefit has been proven; there is a risk of cardiotoxicity and a rise in blood pressure
Citable fact
«Synephrine» — evidence level C. Dosage: 10–50 mg per day as part of complexes; a combination with caffeine is more common. Independent studies of this dose for weight loss are few. Source: PMID 18500382, permanent link to the source in the list below.
How it works
Synephrine (octopamine) is an alkaloid from bitter orange, structurally close to ephedrine but with a lower ability to penetrate the central nervous system. It stimulates alpha- and beta-adrenergic receptors, increasing heart rate, vascular tone and lipolysis. Because of its structural similarity to ephedrine, it is positioned as an “ephedra replacement” in fat-burner complexes, although receptor affinity and effectiveness are substantially lower.
Dosage and intake
10–50 mg per day as part of complexes; a combination with caffeine is more common. Independent studies of this dose for weight loss are few
In complexes it is usually suggested before training or in divided doses during the day. Given the cardiac risks, intake is not recommended
Forms
Bitter orange extract (Citrus aurantium) in capsules, often together with caffeine, guarana and other stimulants. The synephrine content is usually not stated precisely
What is confirmed
- Stimulates beta-adrenergic receptors and theoretically enhances lipolysis
- Positioned as an ephedra replacement
- May slightly increase energy expenditure in some people
Adverse effects and limitations
- The evidence base for reducing fat mass is insufficient; in reviews of weight-loss supplements it is classified as weakly supported
- Cardiotoxicity: cases of myocardial ischemia, coronary artery spasm, arrhythmias and heart attack have been described with its use
- It is positioned as a “natural ephedra replacement”, but this is a marketing claim, not a study conclusion
- There are few publications on safety with long-term use, and the actual content of components in supplements often differs from the label
Interactions
- With caffeine and other stimulants — additive stress on the heart and blood pressure
- With MAO inhibitors — risk of hypertensive crisis
- With antihypertensive drugs and beta-blockers — unpredictable blood pressure reactions
Who must not use it
- Under 18 years: Contraindicated
- Pregnancy and lactation: Contraindicated: a risk to the fetus has been described, and uterine contractions are possible
- Heart disease, arrhythmias, coronary artery disease — contraindicated
- Hypertension — contraindicated
- Taking MAO inhibitors - contraindicated
- Glaucoma, prostatic hyperplasia, hyperthyroidism — contraindicated
- Diabetes mellitus — a possible effect on glucose levels
Sources
- Pharmacology of stimulants prohibited by the World Anti-Doping Agency (WADA) · Docherty JR · British journal of pharmacology, 2008 · PMID 18500382
- Current Evidence to Propose Different Food Supplements for Weight Loss: A Comprehensive Review · Watanabe M, Risi R, Masi D · Nutrients, 2020 · PMID 32962190
See also
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