ECA stands for Ephedrine, Caffeine and Aspirin; these compounds were found to be synergistic for fat loss, and isolating Ephedrine from the Ephedra Sinicus plant and putting it into ECA appears to be quite an effective method of fat loss and neural stimulation.

This page features 20 unique references to scientific papers.

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The ECA stack is a commonly used fat burning stack consisting of Ephedrine, Caffeine, and Aspirin.

The main component, Ephedrine, is the main active ingredient for weight loss and the caffeine augments its efficacy. The aspirin is added to prevent blood clotting (which may be a side effect of ephedrine) and to aid in the signal transduction of ephedrine via prostaglandin inhibition.

Some proponents of the ECA stack recommend replacing the Aspirin in the stack with either Fish Oil or White willow bark, as Aspirin is linked to various organ side effects and the previous two compounds share the same anti-clotting mechanisms.

Studies have shown that the combination of Ephedrine and Caffeine is superior for fat loss than taking each individually.[1][2][3] As ephedrine can increase heart rate and caffeine may increase blood pressure (in a naive user), the combination tends to have an additive rather than synergistic toxicological profile.[4]

Also Known As

Ephedrine/Caffeine/Aspirin, ECA Stack, EC Stack

Caution Notice

The ECA stack is a classical example of combining synergistic stimulants, and thus should be proceeded with caution in somebody not used to either stimulant in these doses. Medical Disclaimer

ECA itself, Ephedrine with Caffeine and Aspirin, has been shown numerous times to be safe and well tolerated although the amount of studies on the subject matter pale in comparison to just EC (Ephedrine and Caffeine).

Actually significant side effects come with either dose abuse (OD-ing on the stuff) or when the ECA is taken vicariously through herbs, like a combination of Ma Huang, Kola Nut, and White Willow Bark (sources of E, C, and A; respectively)

Compounds that can further augment an ECA stacks effectiveness, like Green Tea Catechins or Yohimbine, should be approached cautiously. They can be quite potent, but at the same time can open up one to more side-effects.

Combine it with a good hypocaloric diet and exercise, and perhaps you'll lose 66kg over 13 months like this guy

Kurtis Frank

The Human Effect Matrix looks at human studies (excluding animal/petri-dish studies) to tell you what effect ECA has in your body, and how strong these effects are.
Grade Level of Evidence
A Robust research conducted with repeated double blind clinical trials
B Multiple studies where at least two are double-blind and placebo controlled
C Single double blind study or multiple cohort studies
D Uncontrolled or observational studies only
Level of Evidence
Magnitude of Effect Size
Scientific Consensus Comments
C Metabolic Rate


The increase in metabolic rate seen with ephedrine is augmented with the inclusion of both aspirin and caffeine, hence its notable efficacy

C Weight


Due to both the increase in metabolic rate and reduction in appetite reported, there are notable weight reductions with the ECA stack

C Nasal Congestion


Due to the ephedrine component, ECA may also reduce nasal congestion

C Pain


At least in persons with upper respiratory tract infections, a possible analgesic effect of ephedrine with aspirin exists

C Blood Glucose

No significant alterations in blood glucose noted with ECA supplementation

C Blood Pressure

No significant alterations in long term blood pressure, although acute spikes are possible due to the ephedrine and caffeine components

C Heart Rate

Heart rate at rest is not affected by ECA supplementation and may indirectly be lowered secondary to weight loss. However, an acute increase in heart rate is possible from ... show

C Insulin

No significant alterations in fasting insulin reported

C Total Cholesterol

No significant influence on total cholesterol levels

Three doses of:

  • Ephedrine in 24mg (72mg total)
  • Caffeine in 200mg (600mg total)
  • Aspirin in 81mg (Baby Aspirin) once daily

The ECA stack is usually taken in 6-8 week cycles. Dosages should start off small, before reaching 3 doses a day.


  1. Astrup A, et al The effect and safety of an ephedrine/caffeine compound compared to ephedrine, caffeine and placebo in obese subjects on an energy restricted diet. A double blind trial . Int J Obes Relat Metab Disord. (1992)
  2. Toubro S, et al Safety and efficacy of long-term treatment with ephedrine, caffeine and an ephedrine/caffeine mixture . Int J Obes Relat Metab Disord. (1993)
  3. Astrup A, et al Thermogenic synergism between ephedrine and caffeine in healthy volunteers: a double-blind, placebo-controlled study . Metabolism. (1991)
  4. Haller CA, Jacob P 3rd, Benowitz NL Enhanced stimulant and metabolic effects of combined ephedrine and caffeine . Clin Pharmacol Ther. (2004)
  5. Agonist-Directed Desensitization of the β2-Adrenergic Receptor
  6. Kenakin TP Cellular assays as portals to seven-transmembrane receptor-based drug discovery . Nat Rev Drug Discov. (2009)
  7. Fang Y Label-Free Receptor Assays . Drug Discov Today Technol. (2011)
  8. Fang Y, Ferrie AM Label-free optical biosensor for ligand-directed functional selectivity acting on beta(2) adrenoceptor in living cells . FEBS Lett. (2008)
  9. Receptor internalization and ERK1/2 phosphorylation are dependent on the agonist exposure time
  10. The desensitization and resensitization patterns of quiescent A431 cells induced by epinephrine is sensitive to stimulation duration and several inhibitors
  11. January B, et al beta2-adrenergic receptor desensitization, internalization, and phosphorylation in response to full and partial agonists . J Biol Chem. (1997)
  12. Characterization of β2-Adrenergic Receptor Dephosphorylation: Comparison with the Rate of Resensitization
  13. Sears MR Adverse effects of beta-agonists . J Allergy Clin Immunol. (2002)
  14. Nelson HS Is there a problem with inhaled long-acting beta-adrenergic agonists . J Allergy Clin Immunol. (2006)
  15. Astrup A, et al Enhanced thermogenic responsiveness during chronic ephedrine treatment in man . Am J Clin Nutr. (1985)
  16. Schachtel BP, et al Demonstration of the analgesic efficacy and dose-response of acetylsalicylic acid with pseudoephedrine . J Clin Pharmacol. (2010)
  17. Loose I, Winkel M Clinical, double-blind, placebo-controlled study investigating the combination of acetylsalicylic acid and pseudoephedrine for the symptomatic treatment of nasal congestion associated with common cold . Arzneimittelforschung. (2004)
  18. Horton TJ, Geissler CA Post-prandial thermogenesis with ephedrine, caffeine and aspirin in lean, pre-disposed obese and obese women . Int J Obes Relat Metab Disord. (1996)
  19. Horton TJ, Geissler CA Aspirin potentiates the effect of ephedrine on the thermogenic response to a meal in obese but not lean women . Int J Obes. (1991)
  20. Daly PA, et al Ephedrine, caffeine and aspirin: safety and efficacy for treatment of human obesity . Int J Obes Relat Metab Disord. (1993)

(Common misspellings for ECA include EAC, EC)

(Common phrases used by users for this page include ephedra examine, ec stack, eca stack supplement, eca stack, ec stack, eca aspirin or fish oil)

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