Prohibited Substances in Cycling

Combating doping in cycling is at the center of modern anti-doping efforts. The World Anti-Doping Agency (WADA) publishes an updated list of prohibited substances and methods annually, which applies to all sports, but is particularly strictly monitored in cycling due to historical doping issues. This document provides a comprehensive overview of the various categories of prohibited substances, their mechanisms of action, and the consequences of violations.

Fundamentals of the WADA Prohibited List

The WADA Prohibited List is updated every year on January 1st and includes all substances and methods that meet at least two of the following three criteria:

1. They demonstrably enhance athletic performance
2. They endanger the athlete's health
3. They violate the spirit of sport

The list distinguishes between substances that are prohibited at all times (both in and out of competition) and those that are only prohibited during competition. Additionally, there are specific prohibitions for certain sports.

Main Categories of Prohibited Substances

S0: Non-approved Substances

This category includes all pharmacological substances that are not approved by a health authority for therapeutic use in humans. These include:

• Experimental active ingredients in development
• Medications approved only for veterinary purposes
• Designer drugs without medical approval
• Substances whose approval has been withdrawn

S1: Anabolic Substances

Anabolic substances are prohibited in cycling at all times and are among the most frequently detected doping agents.

Special feature in cycling: Testosterone-Epitestosterone ratio (T/E ratio) is particularly monitored. A value above 4:1 is considered suspicious and can lead to further investigations.

S2: Peptide Hormones, Growth Factors and Related Substances

This category includes highly effective substances that were originally developed for medical treatments:

1. Erythropoietin (EPO) and EPO mimetics - Massively increase the production of red blood cells and thus improve oxygen transport capacity. Historically particularly problematic in cycling.
2. Hypoxia-inducible factor (HIF) stabilizers - Simulate altitude training chemically and stimulate the body's own EPO production.
3. Growth hormone (hGH) - Promotes muscle building, regeneration, and fat burning. Particularly used in the period between races.
4. Insulin-like growth factors (IGF-1) - Support muscle regeneration and building during training phases.
5. Mechanical growth factors (MGF) - Promote muscle growth and repair after intense stress.

S3: Beta-2-Agonists

Beta-2-agonists dilate the bronchi and can improve respiratory performance. Most are prohibited at all times, with important exceptions:

Permitted (in inhalative form with TUE documentation):

• Salbutamol (maximum 1600 µg/24h, not more than 800 µg/12h)
• Formoterol (maximum 54 µg/24h)
• Salmeterol

Prohibited (even inhalative):

• Clenbuterol
• Zilpaterol
• Vilanterol (without TUE)

Important for cyclists: Athletes with asthma must apply for a Therapeutic Use Exemption (TUE) before using permitted substances and document exact dosages.

S4: Hormone and Metabolic Modulators

This category targets substances that manipulate hormones or alter their effects:

1. Aromatase inhibitors - Prevent the conversion of testosterone to estrogen (e.g., Anastrozole, Letrozole)
2. Selective estrogen receptor modulators (SERMs) - Specifically influence estrogen effects (e.g., Tamoxifen, Raloxifene)
3. Myostatin inhibitors - Block the muscle growth-limiting factor myostatin
4. Metabolic modulators - Influence insulin sensitivity and metabolic processes (e.g., Meldonium, GW1516)
5. Peroxisome Proliferator Activated Receptor Delta (PPARδ) agonists - Improve endurance performance and fat metabolism

S5: Diuretics and Masking Agents

Diuretics are primarily misused for two purposes:

1. Weight reduction - Rapid water loss before races in weight-dependent categories
2. Concealment - Dilution of urine to mask other prohibited substances

All diuretics are prohibited, including:

• Furosemide
• Hydrochlorothiazide
• Triamterene
• Acetazolamide

Masking agents additionally include:

• Probenecid (prevents excretion of certain substances)
• Plasma expanders (Dextran, Albumin for blood thinning)
• Epitestosterone (for manipulation of T/E ratio)

Substances Prohibited In-Competition

S6: Stimulants

Stimulants improve attention, reaction time, and can delay fatigue. They are only prohibited in competition:

S7: Narcotics

Narcotic analgesics (strong painkillers) are prohibited in competition:

• Morphine
• Diamorphine (Heroin)
• Fentanyl and derivatives
• Oxycodone
• Hydromorphone

Not prohibited: Codeine, Tramadol (removed from prohibited list since 2024, but still on monitoring list)

S8: Cannabinoids

Natural and synthetic cannabinoids are prohibited in competition:

• Delta-9-tetrahydrocannabinol (THC)
• Synthetic cannabinoids
• CBD (Cannabidiol) is NOT prohibited, but caution regarding product purity

Threshold: THC-COOH (metabolite) above 180 ng/ml in urine is considered a violation

S9: Glucocorticoids

Glucocorticoids (corticosteroids) are prohibited in competition for certain administration forms:

Prohibited:

• Oral intake
• Intravenous, intramuscular, or rectal administration

Permitted (with documentation):

• Topical applications (skin, eyes, ears)
• Inhalative application (with TUE for longer use)

Commonly used substances: Prednisolone, Dexamethasone, Triamcinolone

Prohibited Methods

In addition to substances, certain methods are also prohibited:

M1: Manipulation of Blood and Blood Components

1. Blood transfusions - Autologous or allogeneic blood to increase oxygen transport capacity
2. Artificial enhancement of oxygen uptake - Perfluorochemicals, Efaproxiral, modified hemoglobin
3. Any intravascular manipulation - Mechanical or chemical alteration of blood

M2: Chemical and Physical Manipulation

1. Urine manipulation - Substitution, additives for falsification (proteases, other enzymes)
2. Intravenous infusions - Over 100 ml within 12 hours prohibited (except medical emergencies with TUE)
3. Blood withdrawal and reinfusion - Even smallest amounts for later reinfusion

M3: Gene Doping

1. Transfer of nucleic acids or their sequences
2. Use of normal or genetically modified cells
3. Influence of gene expression through genome editing

Substance-Specific Particularities in Cycling

Testosterone and the T/E Ratio

In cycling, particular attention is paid to the Testosterone-Epitestosterone ratio:

• Normal: T/E ratio is between 1:1 and 2:1 for most people
• Suspicious: Ratio above 4:1
• Procedure in case of suspicion: Long-term metabolite analysis, isotope ratio mass spectrometry (IRMS)

EPO and Erythropoiesis-Stimulating Agents

The EPO problem shaped cycling in the 1990s and early 2000s:

Detection methods:

• Direct detection of recombinant EPO in blood/urine
• Hematocrit threshold (historically 50%, now part of Biological Passport)
• OFF-score in Biological Passport (combines hemoglobin and reticulocytes)

Modern EPO variants:

• CERA (Continuous Erythropoietin Receptor Activator)
• Biosimilar EPO products
• EPO mimetics (e.g., Peginesatide, but rarely misused anymore)

Corticosteroids

Corticosteroids are particularly controversial in cycling because they:

1. Reduce inflammation and suppress pain
2. Can create a feeling of euphoria
3. Have severe side effects with long-term use

UCI additional rule: Since 2022, all corticosteroid applications at UCI races must be reported in advance, including permitted topical applications.

Detection Methods and Detection Limits

The detection period of prohibited substances varies greatly:

Therapeutic Use Exemptions (TUE)

Athletes with proven medical need can apply for a Therapeutic Use Exemption (TUE):

Requirements for TUE:

1. The substance is medically necessary for the treatment of a diagnosed condition
2. No reasonable therapeutic alternative is available
3. The use does not lead to significant performance enhancement beyond normal state
4. The medical indication does not result from previous use of prohibited substances

Common TUE applications in cycling:

• Salbutamol for diagnosed asthma
• Glucocorticoids for severe allergies or inflammation
• ADHD medications (Methylphenidate) for diagnosed ADHD
• Insulin for Type 1 diabetes

Consequences of Violations

Sanctions for doping violations were tightened by the WADA Code 2021:

First violation with intentional doping:

• Sanction: 4 years ban
• Reduction possible to: 2 years with substantial cooperation or admission
• Competition results: Disqualification retroactive from sample collection

First violation without fault:

• Contaminated products: Warning up to 2 years
• Non-specific substances: 2 years (reducible to 1 year)

Repeat violation:

• Sanction: 8 years to lifetime
• No reduction except in extraordinary circumstances

Additional consequences:

• Repayment of prize money
• Loss of medals and titles
• Sponsor contracts are terminated
• Reputation permanently damaged
• Possible criminal prosecution in some countries

Current Developments and Monitoring Program

WADA conducts a monitoring program for substances that are not yet prohibited but are being observed:

2025 on the monitoring list:

• Caffeine - Monitored for abuse patterns (concentrations in urine)
• Tramadol - After prohibition in 2024, still on list to verify compliance
• Nicotine products - Possible performance-enhancing effects are being investigated
• Beta-2-agonists (low doses) - Monitoring of salbutamol concentrations
• Glucocorticoids - Local applications are documented

New substances under observation:

• GW1516 (PPARδ agonist) - Increasingly found on black market
• Aicar (AMPK activator) - Endurance-enhancing potential
• SARMs (Selective Androgen Receptor Modulators) - Wide range of new designer substances
• TB-500 and BPC-157 - Synthetic peptides for regeneration

Risk Groups and Precautions

Risk groups for unintentional violations:

1. Dietary supplement users - Contamination with prohibited substances possible
   Solution: Only use certified products (e.g., Cologne List)
2. Athletes with chronic conditions - Need for medications containing prohibited substances
   Solution: Apply for TUE in time, discuss alternatives with sports physician
3. International athletes - Different trade names and active ingredients in different countries
   Solution: Always check active ingredient, not just trade names, use Global DRO
4. Recreational athletes at mass participation events - Ignorance of regulations
   Solution: Observe WADA Code even at non-professional competitions
5. Returning athletes after injuries - Pain medication and anti-inflammatory drugs
   Solution: Coordinate all medications with team physician, maintain documentation

Prevention and Education

Athlete responsibility:

1. Knowledge of current prohibited list (observe annual updates)
2. Check all medications and dietary supplements
3. Document all substances taken
4. Keep product packaging and package inserts
5. Caution with nutritionists and trainers without anti-doping training
6. Report location for training controls (Registered Testing Pool)
7. Participate in anti-doping education

Support by federations:

• National Anti-Doping Agencies (e.g., NADA Germany)
• UCI Clean Sport Unit
• Team physicians with anti-doping expertise
• Hotlines for consultation (available 24/7)

Technological Advances in Doping Detection

Detection methods are constantly evolving:

Current technologies:

1. High-resolution mass spectrometry - Detects even smallest traces and metabolites
2. Isotope ratio mass spectrometry (IRMS) - Distinguishes between endogenous and synthetic testosterone
3. Dried Blood Spot (DBS) technology - Simplified sample collection and storage
4. Athlete Biological Passport (ABP) - Longitudinal monitoring of blood and steroid profiles
5. Next-generation sequencing - Gene doping detection in development
6. Artificial intelligence - Pattern recognition for suspicious profile changes

Future perspectives:

• Detection of gene editing (CRISPR)
• Improved tests for growth hormone
• Faster turnaround times (results within hours)
• Point-of-care testing at competitions
• Long-term storage of samples for re-tests with future methods (currently 10 years)

Related Topics

• Anti-Doping
• WADA Code
• Testing Procedures
• Famous Doping Cases
• UCI Regulations

Last update: November 2, 2025