Peptide products are becoming increasingly visible online.
From “miracle” weight-loss products like GLP-1 receptor agonists (GLP-1s) and recovery products to treatments marketed for muscle growth or anti-ageing, social media is full of influencers, content creators and online sellers promoting peptides as the latest solution for improving health, appearance or performance.
Some peptide-based medicines are prescribed by doctors for legitimate medical reasons. Others are experimental, poorly understood, or sold online without any safeguards or regulation.
For tennis players, understanding the difference is important.
What are peptides?
The term "peptide" covers a wide range of products and substances. They do not all have the same effects, the same medical purpose, or, crucially, the same anti-doping status.
Peptides are short chains of amino acids that can have a range of effects in the body. GLP-1 medicines such as semaglutide and tirzepatide have helped bring peptides into the mainstream, but they are only one part of a much larger market.
Much of that growth has been driven by social media, where peptides are often promoted as solutions for:
- Rapid weight loss
- Faster recovery
- Muscle growth
- Increased energy levels
- Anti-ageing
As demand has increased, so has the number of off-brand products becoming available online, many of which are not subject to the same rigorous testing required of prescription medications.
This lack of regulation means that, in many cases, the peptide products are not marked as safe (or even approved) for human consumption, and the ingredients can be false, inaccurate, or contain different doses than listed on the label. Players should think very carefully about whether the risk is worth it.
Are peptides prohibited in tennis?
Some are. Some aren't.
This is one of the most important things for tennis players to understand.
The word "peptide" does not tell you whether a substance is allowed or prohibited.
Some peptides are prohibited because they can help the body build muscle, recover faster or provide an unfair performance advantage. At the same time, some peptide-based medicines are allowed in tennis.
The anti-doping status of each substance must be checked individually. Never assume that a product is allowed simply because it is described as a peptide.
When speaking with a healthcare professional about peptide use, ensure that they understand you are subject to doping control. You can also check the ingredients of any prospective medication using websites like GlobalDRO.com, or speak to a member of the ITIA team for further advice.
What about GLP-1 medicines?
GLP-1s are among the best-known peptide-based medicines.
They are used for certain medical purposes, including the treatment of type 2 diabetes and weight management. GLP-1s are not currently prohibited in tennis.
Semaglutide and tirzepatide remain on WADA's Monitoring Program for 2027. WADA uses the Monitoring Program to keep an eye on substances that are not prohibited but are being used by athletes.
Being monitored does not mean a substance is banned, but it does mean that it may become so in the future. WADA’s listing of substances on the Monitoring Program means that it has concerns about the products’ suitability for players’ use, either because they present a risk to the health of sportspeople, or they provide an unfair sporting advantage.
As with any medication, players taking GLP-1s or peptides should ensure that the product has been prescribed by a health professional and is regulated and declare it on your Doping Control Form.
Why is the ITIA talking about peptides?
The biggest concern is not necessarily the peptide itself. It's the source - and not knowing exactly what is in the product you're taking.
In many cases of online purchase, players may have no reliable way of knowing:
- What is actually in the product
- Whether the ingredients match the label
- Whether the product has been manufactured safely
- Whether it contains undeclared substances
This creates both health and anti-doping risks.
What is the anti-doping risk?
Players are responsible for what goes into their body.
If a prohibited substance is found in a sample, saying you didn't know it was there will not protect you from an anti-doping rule violation.
This is similar to the risk associated with supplements.
If you cannot confidently verify what is in a product, you are taking a risk.
What is the health risk?
Many peptide products have not been approved for human use, often due to health risks found during clinical trials.
Moreover, products bought online or from unofficial sources may contain:
- Incorrect doses
- Contaminants
- Different ingredients from those listed on the label
- Ingredients that are not disclosed at all
Without appropriate medical supervision, this can present significant health risks.
A social media recommendation should never replace advice from a qualified healthcare professional.
How can players protect themselves?
Before taking any peptide-based product:
- Speak with a qualified healthcare professional.
- Check the anti-doping status of the substance.
- Use licensed pharmacies and legitimate suppliers.
- Be cautious of products promoted primarily through social media.
- Avoid purchasing products from unofficial or unverified online sources.
- Be sceptical of products promising rapid or dramatic results.
- Ask for advice if you are unsure.
Your health and your tennis career are too important to leave to chance.
If you're unsure about a medication, supplement or peptide product, contact us on The Line to speak with a member of the ITIA team.
Published 07 October 2026 12:00
