The Peptide Desk The Peptide Desk

This information is for research and educational purposes only. No medical recommendations. Products are not approved for human use. For health questions, consult a doctor.

Lexicon
Muscle & performance

EPO

Erythropoietin increases red blood cell production, medically against anemia, infamous in endurance sport and with serious risks.

3 min read 8 sources

To the product To the sources
Vial with white powder, a blue cap and a black TPD label for EPO on a white podium, next to it a large, branched molecule model of blue glass spheres in a bright lab
Compound approved · since 1989, only for anaemia

Summary

At a glance

Sources checked on 26 Oct 2026

Structure
165 amino acids

Glycoprotein with four sugar chains, made mainly in the kidney1

First approval (epoetin alfa)
1,989

according to ChEMBL, approved for certain forms of anaemia8

VO2max in the lab test
+4.7 %

Cyclists after 8 weeks of EPO versus placebo, no difference in the race2

More serious events
+34 %

higher versus lower Hb target in kidney disease (hazard ratio 1.34)3

Clots in vessels
2 -fold

2.8 versus 1.4 percent with and without EPO in breast cancer on chemotherapy5

  • EPO (erythropoietin) is a hormone the body makes in the kidney. In the bone marrow it keeps the precursors of red blood cells alive and lets them divide.1
  • Recombinant EPO has been approved as a medicine since 1989, but only for certain forms of anaemia, for example in kidney disease or during chemotherapy.81
  • In well-trained cyclists maximal oxygen uptake in the lab test rose by about 4.7 percent. In a real mountain race, however, they were not faster than on placebo.2
  • Too much is dangerous: a higher haemoglobin target in kidney disease led to about 34 percent more deaths, heart attacks, heart failure and strokes. Clots in vessels occurred twice as often on EPO.35
  • EPO is banned in sport. Everything here is research, not a recommendation.2
Profile

Updated May 2026

Class
Erythropoietin

hormone, growth factor

Use
Subcutaneous

in IU

Half-life
hours

effect days

WADA
Banned

category S2

Sizes
3000IU/5vials

1 size in the shop

Contents 16 sections
  1. At a glance
  2. What is EPO?
  3. How it works
  4. What you need
  5. Mixing and units
  6. Dosing (in IU)
  7. Injection
  8. What the research shows
  9. Research status
  10. Side effects
  11. Practice
  12. Storage
  13. Related compounds
  14. FAQ
  15. Glossary
  16. Sources

What is EPO?

EPO (erythropoietin) is an endogenous hormone that stimulates the production of red blood cells. Medically, recombinant EPO is used mainly against anemia, for example in kidney disease or under chemotherapy. In endurance sport it is infamous as a doping agent, because more red blood cells mean more oxygen transport.

Important and honest up front: EPO thickens the blood and has serious cardiovascular risks. It is not a harmless performance agent.

Comparison

The body's own hormones as compounds

Each of these hormones has its own receptor. EPO acts almost only on blood formation.

Hormone of blood formation EPO EPOR
Growth hormone HGH 191AA (Somatropin) GH IGF-1 analogue IGF-1 LR3 IGF-1

8

How it works

EPO binds receptors in the bone marrow and stimulates the production and maturation of red blood cells there. More red blood cells means more hemoglobin and thus more oxygen transport, which can increase endurance performance. But exactly this raised hematocrit is also the problem: the blood gets thicker and the risk of clots rises.

Where it acts

One receptor, several consequences

Tap a point or a card. Colour = receptor, grey = observed in studies.

  1. Kidney

    Makes EPO when oxygen is low, controlled by HIF. In kidney disease it is lacking, hence the anaemia1

    Observed in trials
  2. Bone marrow

    Precursors of red blood cells survive and divide1

    EPOR
  3. Blood and vessels

    Haemoglobin rises, clots in vessels occurred twice as often5

    Observed in trials
  4. Heart and circulation

    Higher Hb target: more deaths, heart attacks, heart failure and strokes3

    Observed in trials
  5. Endurance

    VO2max higher in the lab, mountain race not faster2

    Observed in trials

Targets in the ChEMBL database8

Compound CHEMBL1201565: one recorded mechanism, agonist with direct binding to the human receptor.

Erythropoietin receptor
Gene
EPOR
UniProt
P19235
ChEMBL
CHEMBL1817
Action
Agonist, direct binding
Porous glass cross-section of bone with a cavity, inside it blue molecules dock and red disc-shaped glass blood cells form
EPO stimulates the formation of red blood cells in the bone marrow. Symbolic image.

What you need

Supplies

2 things, numbered as in the picture

Tick off what you already have. Vial and BAC water are our real shop photos at the same size.

EPO vial and bacteriostatic water at the same size with the black TPD label, next to two U-100 insulin syringes, two alcohol swabs and a sharps container with a blue lid

  1. EPO vial

    The EPO vial (labeled in IU, often 3000 IU).

    In the shop

  2. Syringes and swabs

    U-100 insulin syringes, alcohol swabs.

    Amazon (opens a new tab)

As an Amazon associate we earn from qualifying purchases. Links open Amazon - no extra cost for you.

Mixing and units

EPO is given in IU (international units), not in mg. Many EPO preparations come as a ready solution or with a defined IU per vial (e.g. 3000 IU per vial).

  • The IU count per vial is on the label, the partial amount follows from that.
  • Dose precisely, EPO is very potent in small amounts.

Step by step

Dissolving the powder

Four steps, the same for every vial size.

  1. 1Wipe the cap

    Clean the rubber stopper with an alcohol swab.

  2. 2Add BAC water

    Just add it, it does not matter if it hits the powder directly.

  3. 3Swirl or shake

    Until everything has dissolved, both are fine.

  4. 4Draw up

    With the U-100 insulin syringe.

Less water higher concentration fewer units on the syringe

Dosing (in IU)

Dosing

Dosing, titration and syringe

Loading the dosing information …

  • Getting started and stepping up, drawn as a staircase
  • Units on the U-100 syringe for every step
  • How long one vial lasts

Injection

The injection is subcutaneous, into the fat layer under the skin. Common spots are the abdomen (keep about two finger-widths clear of the navel), the front and the inner side of the thigh, or the back of the upper arm.

The short version:

Injection

Where and at what angle

Pick a spot or switch the angle. Subcutaneous means: into the fat layer, not the muscle.

Rotate the spot each time, never the same one twice in a row.

90°More fat under the skin

Rule of thumb: where there is more fat under the skin, insert straight at 90 degrees. In lean people with little fat, 45 degrees, so the needle stays in the fat layer. Simplified diagram.

  1. Clean the spot with an alcohol swab and let it dry

  2. Pinch up a small fold of skin

  3. Insert the needle: at 90 degrees where there is more fat under the skin, at 45 degrees in lean people with little fat

  4. Inject slowly, wait a moment, then withdraw

  5. Put the needle straight into the sharps container

Rotate the site each time so the tissue does not get irritated. Never the same spot twice in a row.

What the research shows

EPO is very well understood as a hormone and drug (overview: Jelkmann, 2013): it is the central regulator of red blood cell formation and medically established against anemia. The performance-enhancing effect in endurance sport is real, but so are the documented cardiovascular risks from the thickened blood.

Study results

What the trials measured

Interactive: switch tabs, tap points, show or hide arms. Arms are named relative to each other, no dosing advice.

Performance after 8 weeks of EPO2

Difference from the placebo group in percent, 48 well-trained amateur cyclists

Maximal oxygen uptake (VO2max)2 Step test in the lab
Placebo or without EPO 0.0%
With EPO +4.7%
Maximal power (watts)2 Step test in the lab
Placebo or without EPO 0.0%
With EPO +3.0%
Time in the mountain race2 Mont Ventoux, no measurable difference
Placebo or without EPO 0.0%
With EPO +0.3%

VO2max and watts calculated from the means in the abstract. Race time was 0.3 percent higher with EPO, so slightly slower, without a measurable difference. The 45-minute test just below maximal effort showed no difference either.

Blood transfusions in breast cancer5

Share of patients with a transfusion, 2,098 women on chemotherapy

At least one transfusion5 EPO versus standard care
Placebo or without EPO 11.4%
With EPO 5.8%

Fewer transfusions with EPO. The trial missed its goal of ruling out a higher risk of tumour progression, though. The authors therefore recommend transfusions rather than EPO for this group.

Stack of red glass blood cells next to a frosted glass kidney on a bright lab bench, sample racks with tubes behind them
EPO is well studied as a hormone and a drug. The same goes for the risks of thicker blood. Symbolic image.

Research status

Where the research stands

EPO has been approved for decades. The registry lists 658 trials with epoetin alfa and 194 with epoetin beta. Here are the large trials this page draws on. As of 26 Oct 2026. 7

  1. Preclinical Kidney hormone that controls red blood cell production
  2. Phase 1 no registered trial
  3. Phase 2 no registered trial
  4. Phase 3 3 trials, 2 completed
  5. Approval since 1989, only for anaemia
5,203 participants in phase 3 Planned figures for running trials Approved as a medicine (epoetin alfa according to ChEMBL since 1989), but only for certain forms of anaemia. Not approved for performance, banned in sport.8
Show all 4 phase 3 and 4 trials on a timelineHide timeline 2 completed 1 running 1 stopped early 3 with results
Phase 3
Phase 4

Bar: start to primary endpoint (planned for running trials). Green = completed, blue = progress until 26 Oct 2026, grey = stopped early.

Side effects

  • Central risk: blood too thick (high hematocrit), causing thrombosis, heart attack, stroke.
  • High blood pressure.
  • Flu-like symptoms, local reactions.

Tolerability

Risks in large trials

Per 100 people: how many had a serious event. Left the comparison of two Hb targets in kidney disease, right with and without EPO in breast cancer.

14 of 100 Lower Hb target
18 of 100 Higher Hb target
Event Lower Hb targetHigher Hb target
Death, heart attack, heart failure or stroke3 14%18%
Clots in vessels (thromboses)5 0%0%

Values for the kidney trial calculated from the event counts (125 of 715 versus 97 of 717). The trial was stopped early because the higher target showed more harm. Raised blood pressure, headaches and flu-like symptoms come on top.364

Practice

  1. Without regular hematocrit control EPO is especially dangerous.

  2. Enough fluids, do not thicken the blood further.

  3. With cardiovascular risk, leave it alone.

  4. Banned in official competition (WADA S2).

Carafe and glass of water, a pair of light blue running shoes, a white cube and a rack of empty sample tubes on a white table

Storage

EPO comes either as a ready-made solution or as a powder you mix yourself. Store the ready-made solution as the pack and the prescribing information say: refrigerated throughout (2 to 8 degrees), not frozen, protected from light.

Once mixed from powder, it keeps for at least 4 to 6 months in the fridge (2 to 8 °C). Here too, do not freeze and protect from light.

Nine vials with white powder and blue caps in the door shelf of a bright fridge
Ready-made solution refrigerated throughout as the pack says (2 to 8 degrees), mixed from powder it keeps there for at least 4 to 6 months. Do not freeze, protect from light. Symbolic image.

Related

Related compounds

A different path: all in the TPD lexicon.

EPO
HGH 191AA (Somatropin) Different hormone, own receptor IGF-1 LR3 Growth factor, different path HCG Different hormone, focus on testes and testosterone

FAQ

Common questions about EPO

Short answers, each backed by the sources below.

Is EPO approved?

Yes, as a medicine, but only for certain forms of anaemia, mainly in kidney disease and during chemotherapy. According to ChEMBL epoetin alfa has been approved since 1989, further forms such as epoetin beta followed. It is not approved for more endurance.81

How does EPO work?

The kidney makes EPO when oxygen is scarce. This is controlled by the HIF proteins. In the bone marrow EPO binds to its receptor and keeps the precursors of red blood cells alive, so they divide and mature. More red blood cells means more haemoglobin, but also thicker blood.1

Does EPO help in endurance sport?

In the lab yes, on the road hardly. In a trial with 48 well-trained cyclists maximal oxygen uptake rose by about 4.7 percent and peak power by about 3 percent after 8 weeks. In the 45-minute test just below that and in the race up Mont Ventoux, however, they were no faster than the placebo group.2

Why is a high haemoglobin level risky?

Because the blood gets thicker. In 1,432 people with kidney disease a higher Hb target led to 125 serious events (death, heart attack, heart failure, stroke), the lower one to 97. The trial was therefore stopped early. A second large trial found no protection for the heart from full correction, while more people needed dialysis (127 versus 111).364

What is known about EPO in cancer?

In a trial with 2,098 women with breast cancer on chemotherapy fewer needed a transfusion with EPO (5.8 versus 11.4 percent). Clots in vessels were twice as common, though (2.8 versus 1.4 percent). A higher risk of tumour progression could not be ruled out with certainty. The authors therefore recommend transfusions in this group.5

Is EPO allowed in sport?

No. EPO counts as doping and is banned in competition. That is exactly why the Dutch anti-doping authority helped test its effect in a trial of its own, with the result above: lab test better, race not.2

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

Anaemia
Too little haemoglobin in the blood, so the body gets less oxygen.
Bone marrow
Tissue inside the bones where blood cells are made.
Erythropoietin
Hormone from the kidney that stimulates red blood cell production in the bone marrow. Abbreviated EPO.
Haematocrit
Share of red blood cells in the blood volume. The higher it is, the thicker the blood flows.
Haemoglobin
Red pigment in red blood cells that carries oxygen. Abbreviated Hb.
HIF
Hypoxia-inducible factors: proteins that switch on genes such as the one for EPO when oxygen is low.
IU (international unit)
A measure of activity, not of weight. EPO is given in IU, not in milligrams.
Placebo
Dummy preparation without active substance. Comparing against it shows what is due to the substance itself.
Thrombosis
A blood clot that blocks a vessel. Can lead to pulmonary embolism, heart attack or stroke.
VO2max
Maximal oxygen uptake: how much oxygen the body can use per minute at full effort.

Evidence

Sources

Show all 8 sourcesHide sources 5 Studies2 Trial registry1 Database checked 26 Oct 2026

Studies

  1. Review of the physiology and pharmacology of EPO

    Jelkmann, Transfusion Medicine and Hemotherapy, 2013

    DOI 10.1159/000356193 PMID 24273483
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  2. EPO versus placebo in well-trained cyclists

    Heuberger et al., The Lancet Haematology, 2017

    DOI 10.1016/S2352-3026(17)30105-9 PMID 28669689
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. CHOIR: two Hb targets in kidney disease

    Singh et al., New England Journal of Medicine, 2006

    DOI 10.1056/NEJMoa065485 PMID 17108343 NCT00211120
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. CREATE: full early correction of anaemia in kidney disease

    Drüeke et al., New England Journal of Medicine, 2006

    DOI 10.1056/NEJMoa062276 PMID 17108342 NCT00321919
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  5. EPO versus standard care in breast cancer on chemotherapy

    Leyland-Jones et al., Journal of Clinical Oncology, 2016

    DOI 10.1200/JCO.2015.63.5649 PMID 26858335 NCT00338286
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. CHOIR on the registry: stopped by the safety board

    ClinicalTrials.gov, NCT00211120

    NCT00211120
    Checked 26 Oct 2026 via ClinicalTrials.gov API v2
  2. Trials with epoetin alfa on ClinicalTrials.gov

    ClinicalTrials.gov, U.S. National Library of Medicine

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Epoetin alfa in ChEMBL: approval and target

    ChEMBL, EMBL-EBI (CHEMBL1201565)

    Checked 26 Oct 2026 via ChEMBL

In the shop

EPO in the catalog

Sizes, prices and shipping times are on the product page.

To the product