supplementNot FDA-approvedOTC supplementSynephrine from bitter orange (Citrus aurantium) is sold in the US as an unregulated dietary supplement, commonly in weight-management and pre-workout productsCardiovascular safety signals (elevated blood pressure and heart rate, especially combined with caffeine) are discussed in the cited safety review
SynephrineBenefits, Dosage & Interactions
Also known as: Bitter Orange, Citrus aurantium
Synephrine, a naturally occurring alkaloid, is primarily found in the fruit of Citrus aurantium, commonly known as bitter orange. This compound shares structural similarities with epinephrine (adrenaline) and ephedrine, which are known for their stimulant properties. Research on Synephrine focuses on weight loss.
How much Synephrine do people take?
The cited review summarizes bitter orange/synephrine products dosed in the range of a few milligrams to around 50 mg of synephrine per serving in human studies it surveys. Route reported: Oral, typically as a standardized bitter orange extract in capsules or weight-management blends. Frequency reported: Once to several times daily depending on the product studied. These are amounts documented in the cited studies and labels for Synephrine — they are reported for reference, not a recommendation. Regulatory status differs by country, including between the US (FDA) and Canada (Health Canada). Confirm any amount with a licensed clinician before you take it.
See the full reported protocol and its sourcesResearched by DoseRoutine Research TeamReviewed for accuracy by Nicholas Alexander, RSE, SO, PMPLast updated Educational reference only — not medical advice. Always confirm dosing and safety decisions with a licensed clinician.
Evidence: Limited — Human observational or case data only — no randomized trials.
Evidence strengthLimited · 2/4
PreclinicalStrong human evidence
Human observational or case data only — no randomized trials.
Plasma half-life
Not applicable
Typical timing
in the morning
Food rule
on an empty stomach
Default unit
mg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
- Reported amounts
- The cited review summarizes bitter orange/synephrine products dosed in the range of a few milligrams to around 50 mg of synephrine per serving in human studies it surveys[1]
- Route studied
- Oral, typically as a standardized bitter orange extract in capsules or weight-management blends[1]
- Frequency
- Once to several times daily depending on the product studied[1]
Reported for Synephrine in the cited sources. Published ranges are not dosing advice.
References & evidence
Documents the Synephrine entry is written from. Each number matches an inline marker above.
- [1]Safety, Efficacy, and Mechanistic Studies Regarding Citrus aurantium (Bitter Orange) Extract and p-SynephrinePhytotherapy Research · 2017 · Peer-reviewed · PMID 28752649
- [2]Bitter OrangeLiverTox / NCBI Bookshelf drug monograph · 2006 · Reference database · PMID 30000952
References & Evidence
Sources on this page that document Synephrine dosing, timing and safety.
- [1]National Center for Biotechnology Information View source
Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.
What is Synephrine studied for?
What is Synephrine?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.
Synephrine, a naturally occurring alkaloid, is primarily found in the fruit of *Citrus aurantium*, commonly known as bitter orange. This compound shares structural similarities with epinephrine (adrenaline) and ephedrine, which are known for their stimulant properties. Traditionally, bitter orange has been used in various cultures for its perceived medicinal properties, including digestive support. In modern contexts, synephrine has gained attention as a dietary supplement, particularly for its potential role in weight management and athletic performance.
Bitter orange has a long history of use in traditional Chinese medicine and as a flavoring agent. Its fruit extract, standardized for synephrine content, is now marketed in various forms, including capsules, powders, and as an ingredient in multi-ingredient supplements. While often associated with weight loss, research on synephrine's efficacy and safety is ongoing, necessitating a careful review of available evidence. (PubChem, Examine.com)
What does the research say about Synephrine?
Tap a section to expand.
The proposed mechanism of action for synephrine revolves around its interaction with adrenergic receptors, specifically beta-3 adrenergic receptors. These receptors are primarily involved in the regulation of lipolysis (fat breakdown) and thermogenesis (heat production) in adipose tissue. By stimulating these receptors, synephrine may potentially increase metabolic rate and fat oxidation, contributing to energy expenditure.
However, synephrine's activity is generally considered less potent than that of ephedrine, and its affinity for alpha-1 and beta-1/2 adrenergic receptors (which can affect heart rate and blood pressure more significantly) appears to be lower. Some research suggests that synephrine may also influence appetite by interacting with certain brain pathways, although this aspect of its mechanism is less thoroughly understood. The exact physiological effects can depend on the specific isomer of synephrine (e.g., *p*-synephrine, *m*-synephrine, *o*-synephrine) present in a given extract, with *p*-synephrine being the most common isomer found in *Citrus aurantium* and the most frequently studied in supplements. (DrugBank, NIH ODS)
Source for this section: Sources for How does Synephrine work?: Jumps to this entry in the sources and references list at the end of the page.
Research into the potential benefits of synephrine primarily focuses on its effects related to metabolism and weight management. Studies have explored its role in:
* **Energy Expenditure:** Some human studies suggest that synephrine supplementation, particularly *p*-synephrine, may lead to a modest increase in resting metabolic rate. This effect is thought to contribute to a higher overall calorie expenditure throughout the day. (Examine.com)
* **Fat Oxidation:** There is some evidence that synephrine might enhance the body's ability to burn fat for energy (fat oxidation), especially during physical activity. This could potentially be beneficial for individuals looking to reduce body fat. (Cochrane)
* **Appetite Control:** While less consistently evidenced, some hypotheses suggest that synephrine might have mild appetite-suppressing effects, which could indirectly support weight loss efforts. However, this area requires more robust research. (PubChem)
It is important to note that many studies investigating synephrine's effects often use it in combination with other ingredients like caffeine. The results of these combination studies may not be solely attributable to synephrine, making it challenging to isolate its individual benefits. The observed effects are generally modest, and synephrine is not considered a 'miracle' weight-loss solution. (NIH ODS)
The scientific evidence supporting synephrine's benefits, particularly for weight loss, is considered moderate. Several human clinical trials and systematic reviews have investigated its effects. For instance, a review published in the *Journal of Medicinal Food* analyzed multiple studies and concluded that *p*-synephrine, alone or in combination with other compounds, appears to increase resting metabolic rate and energy expenditure, albeit modestly. Another systematic review highlighted that while some studies show positive effects on thermogenesis and fat oxidation, larger, longer-term studies are needed to confirm significant clinical benefits for weight loss in diverse populations.
Many studies commonly administer synephrine at dosages in the range of 10 to 50 mg, one to three times daily. However, individual needs and responses can vary significantly, and the impact of synephrine can be influenced by other lifestyle factors such as diet and exercise. The quality and purity of synephrine products can also vary. While often studied for its stimulant properties, care must be taken when interpreting results due to potential confounding factors present in many studies, such as the co-administration of caffeine or other thermogenic ingredients. (Cochrane, Examine.com)
While generally considered safe for healthy individuals at commonly studied dosages, synephrine can cause side effects. These are often related to its stimulant properties and may include:
* Increased heart rate
* Elevated blood pressure
* Headache
* Anxiety or nervousness
* Insomnia or sleep disturbances
* Gastrointestinal upset (e.g., nausea, indigestion)
These side effects are typically mild and transient, but their severity can increase with higher dosages or in individuals sensitive to stimulants. There have been reports of more serious cardiovascular events, though these are often associated with products containing synephrine alongside other stimulants or in individuals with pre-existing heart conditions. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Individuals with pre-existing medical conditions, particularly cardiovascular diseases such as high blood pressure, arrhythmias, or a history of heart attack or stroke, should exercise extreme caution or avoid synephrine altogether. Its stimulant effects can exacerbate these conditions. People with thyroid disorders, glaucoma, or psychiatric conditions should also consult a healthcare professional before use due to potential interactions or worsening of symptoms. Synephrine should not be used by pregnant or breastfeeding individuals due to insufficient safety data. If you experience symptoms such as chest pain, dizziness, or severe palpitations after taking synephrine, seek immediate medical attention. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Synephrine is contraindicated in individuals with known hypersensitivity to bitter orange or any of its components. It should not be used by individuals with uncontrolled hypertension, severe cardiovascular disease, angina pectoris, or a history of cardiac arrhythmias. Patients undergoing surgery should discontinue synephrine at least two weeks prior, as it may interfere with blood pressure and heart rate regulation during anesthesia. Individuals diagnosed with pheochromocytoma, glaucoma, or anxiety disorders are also advised against its use. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Synephrine should not be combined with other stimulants, including caffeine, ephedrine, yohimbine, or other thermogenic compounds, as this can amplify its effects and significantly increase the risk of adverse cardiovascular events such as increased heart rate, blood pressure, and potential arrhythmias. It should also be avoided by individuals taking monoamine oxidase inhibitors (MAOIs) due to the risk of hypertensive crisis. Care should be taken when combining synephrine with medications that affect heart rate or blood pressure, including alpha-adrenergic agonists and beta-blockers. Consult with a healthcare provider before combining synephrine with any prescription medications or other supplements. This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Often, synephrine is taken in the morning to align with its potential metabolic-boosting effects and to avoid interference with sleep. Due to its half-life of approximately 2 hours, multiple doses throughout the day might be considered in some study protocols, typically spaced several hours apart. Some individuals prefer to take it before exercise to potentially enhance fat oxidation during physical activity. For most individuals, taking synephrine on an empty stomach is common to potentially improve absorption; however, this can sometimes increase the likelihood of gastrointestinal upset. If stomach upset occurs, taking it with a light meal might be an alternative. Individual responses to timing and food intake can vary. The dose is user-directed and must be set by a licensed clinician.
Source for this section: Sources for When should you take Synephrine?: Jumps to this entry in the sources and references list at the end of the page.
Put it into practice
Reading about Synephrine is the first step — DoseRoutine helps you act on it. These free tools turn what you just learned into a routine.
What interacts with Synephrine?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Any glp1 + supplement | Note | Category ruleConfidence: theoretical | GLP-1 medications slow stomach emptying, changing how/when oral supplements absorb; rapid weight loss raises the importance of protein and micronutrients.Source pending | Time oral supplements when nausea is lowest; prioritize protein and micronutrients; discuss with your provider. |
| Any supplement + medication | Note | Category ruleConfidence: theoretical | Some supplements change how the body processes medications (absorption, liver enzymes, or additive effects).Source pending | Specific pairs are checked against a licensed drug database and shown with their own severity. Always confirm with your provider or pharmacist. |
| Phenelzine | Avoid | Compound pairConfidence: theoretical | MAOI blocks catecholamine breakdown; combining with sympathomimetics can trigger hypertensive crisis.Source pending | Do not combine. |
| Tranylcypromine | Avoid | Compound pairConfidence: theoretical | MAOI blocks catecholamine breakdown; combining with sympathomimetics can trigger hypertensive crisis.Source pending | Do not combine. |
| Selegiline | Avoid | Compound pairConfidence: theoretical | MAOI blocks catecholamine breakdown; combining with sympathomimetics can trigger hypertensive crisis.Source pending | Do not combine. |
Frequently asked questions about Synephrine
Synephrine is a natural alkaloid found primarily in bitter orange (*Citrus aurantium*). It is structurally similar to stimulants like ephedrine and epinephrine and is often used in dietary supplements for its perceived effects on metabolism and weight management.
Synephrine is thought to work by stimulating beta-3 adrenergic receptors, which can increase thermogenesis (heat production) and lipolysis (fat breakdown), potentially leading to increased energy expenditure. It may also have mild effects on appetite.
At commonly studied doses, synephrine is generally considered safe for healthy individuals. However, it can cause stimulant-related side effects such as increased heart rate, blood pressure, anxiety, and insomnia. Individuals with pre-existing heart conditions or those sensitive to stimulants should use caution or avoid it.
Combining synephrine with other stimulants, including caffeine, is generally not recommended. This combination can increase the risk and severity of adverse cardiovascular side effects like elevated heart rate and blood pressure.
Synephrine has an approximate half-life of 2 hours, meaning about half of the compound is eliminated from the body within this timeframe. Its effects typically last for several hours after ingestion.
Interaction risk for Synephrine comes from the rest of the stack: other supplements, prescription medicines, hormone therapy and peptides. Because Synephrine is usually taken in the morning, most avoidable conflicts come from what else lands in that same window. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers Synephrine with no sign-up.
Synephrine is typically taken in the morning. Published protocols usually have it taken on an empty stomach. Published ranges differ between studies and formulations — the dose to use is the one on your label or from your clinician.
There is no single answer for Synephrine plus TRT. What matters is the specific protocol you are on and what your most recent hormone panel shows. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
Pairing Synephrine with peptides has to be assessed one peptide at a time, because GLP-1 agonists, secretagogues, healing peptides and melanocortins do not share an interaction profile. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
Published frequency for Synephrine varies by protocol and formulation, so the label or prescription is what sets it. It is typically taken in the morning. Most protocols have it taken on an empty stomach. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
The effect of a missed dose of Synephrine depends on the protocol and formulation you are on. Doubling up to "catch up" is generally not appropriate unless the label or prescriber says so. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For Synephrine the useful record is the dose, the time it was actually taken, and what else was taken in the same window. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
The cited review summarizes bitter orange/synephrine products dosed in the range of a few milligrams to around 50 mg of synephrine per serving in human studies it surveys. Route reported: Oral, typically as a standardized bitter orange extract in capsules or weight-management blends. Frequency reported: Once to several times daily depending on the product studied. These are amounts documented in the cited studies and labels for Synephrine — they are reported for reference, not a recommendation. Regulatory status differs by country, including between the US (FDA) and Canada (Health Canada). Confirm any amount with a licensed clinician before you take it.
Which studies looked at Synephrine?
Peer-reviewed research indexed in PubMed. Each entry links to the original record.
- 1.p-Synephrine, ephedrine, p-octopamine and m-synephrine: Comparative mechanistic, physiological and pharmacological properties(opens PubMed in a new tab)Phytother Res · 2020 · PMID 32101364 · https://pubmed.ncbi.nlm.nih.gov/32101364/
Sources cited on this page
Specific documents referenced by the numbered markers above. Each number matches the marker in the text.
- PubChem CID 7172(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/7172
Verify at
Publisher search links for Synephrine. These are places to check the information — they are not citations, so they are not numbered.
- Examine.com(publisher search, opens in a new tab)Examine.com · publisher search
- NIH Office of Dietary Supplements(publisher search, opens in a new tab)National Institutes of Health · publisher search
- DrugBank(publisher search, opens in a new tab)DrugBank Online · publisher search
- Mayo Clinic(publisher search, opens in a new tab)Mayo Clinic · publisher search
- Cochrane Library(publisher search, opens in a new tab)Cochrane · publisher search
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- DailyMed labeling archive(publisher search, opens in a new tab)U.S. National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on Synephrine?
Plain-text summary, safe to quote verbatim:
Synephrine, a naturally occurring alkaloid, is primarily found in the fruit of Citrus aurantium, commonly known as bitter orange. This compound shares structural similarities with epinephrine (adrenaline) and ephedrine, which are known for their stimulant properties. Research on Synephrine focuses on weight loss.
Source: DoseRoutine — https://doseroutine.com/library/synephrine
Synephrine cheat sheet
DoseRoutine cheat sheet · Supplement
Synephrine
Synephrine, a naturally occurring alkaloid, is primarily found in the fruit of Citrus aurantium, commonly known as bitter orange. This compound shares structural similarities with epinephrine (adrenaline) and ephedrine, which are known for their stimulant properties.
Evidence
Limited
Human observational or case data only — no randomized trials.
Studied range
The cited review summarizes bitter orange/synephrine products dosed in the range of a few milligrams to around 50 mg of synephrine per serving in human studies it surveys
Route
Oral, typically as a standardized bitter orange extract in capsules or weight-management blends
Frequency studied
Once to several times daily depending on the product studied
Timing
in the morning
With food
on an empty stomach
Not FDA-approvedOTC supplementSynephrine from bitter orange (Citrus aurantium) is sold in the US as an unregulated dietary supplement, commonly in weight-management and pre-workout productsCardiovascular safety signals (elevated blood pressure and heart rate, especially combined with caffeine) are discussed in the cited safety reviewWeight Loss
Studied ranges, not dosing advice. Not medical advice — talk to a clinician. doseroutine.com/library/synephrine
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). Synephrine — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/synephrine
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