Marina, an amateur runner aged 34, took a weight-loss tea purchased at a street fair in the week of a 10 km competition. She had never used any type of substance to enhance performance, but was drawn for routine anti-doping testing at the competition. Two weeks later, she received a call informing her that the result had come back positive. The "culprit" was a stimulant present in the tea's composition, which was not even listed on the label. Cases like this happen more frequently than one might imagine, and that is what we are going to discuss here.

"The data and clinical case cited in this article are fictitious and are purely illustrative in purpose, serving to facilitate understanding of the subject matter addressed."

What is doping, after all?

Doping is the use of substances or methods prohibited by anti-doping agencies, such as WADA (World Anti-Doping Agency), with the aim of improving physical performance in a sports competition. But the concept goes beyond "the athlete who cheats on purpose": the international rule considers doping to be the simple presence of the prohibited substance in the body, regardless of the person's intention. In other words, it is possible to "test positive for doping" without ever having sought any advantage.

For a substance to enter the prohibited list, it generally needs to meet at least two of these three criteria: having the potential to improve sports performance, representing a health risk to the athlete, or violating the so-called "spirit of sport" (fair play, honesty, respect for rules).

What does "test positive for doping" mean?

In sports practice, "testing positive for doping" means having a positive result in an anti-doping test, either because the person actually used a substance to improve performance, or because of an episode of contamination or unintentional use. This second scenario is called accidental doping, and it is more common than it seems: over-the-counter medications, dietary supplements and even teas can contain substances from the prohibited list without this being clear on the packaging.

Some common medications that can lead to this type of situation:

  • Cold and decongestant medicines, which often contain ephedrine, pseudoephedrine or phenylephrine
  • Some cough syrups, which may have codeine in the formula
  • Corticosteroids in certain routes of administration
  • Diuretics, used for high blood pressure, which also serve to "mask" other substances and for this reason are closely monitored
  • Beta-blockers, used for arrhythmias and anxiety, prohibited in sports that require a steady hand, such as sport shooting
  • Bronchodilators for asthma, which at specific doses or routes enter the list

In Brazil, this concern prompted a recent change: Law 14,806/2024 now requires that package inserts and labels of medications inform whether the product contains a substance prohibited in sport, precisely to reduce the risk of accidental doping.

And what about teas? Do they also come into the picture?

Yes, and one of the best-known examples is coca leaf tea, traditional in Andean countries such as Peru and Bolivia, where it is offered to tourists to alleviate altitude sickness. The coca leaf is the same plant from which cocaine is extracted, and even in small amounts, typical of a cup of tea, the body absorbs enough for a metabolite of the substance, benzoylecgonine, to appear in the urine hours later. There have been cases of professional football athletes who tested positive after consuming this tea during travels, claiming to be unaware of the beverage's composition.

Other teas and "natural mixtures" that deserve attention:

  • Weight-loss or "detox" teas sold without regulation, which sometimes have hidden stimulants in the formula, not listed on the label
  • Teas or infusions with ephedra (Ma Huang), a plant rich in ephedrine
  • Drinks made with guarana or cola nut in large quantities, due to concentrated caffeine

It is worth noting that caffeine, in itself, is not currently a prohibited substance by WADA. It is only on the monitoring programme, that is, it is observed, but does not generate punishment. The real problem lies in unregulated "natural" products, which may contain undeclared stimulants.

Consequences of using these substances

The consequences appear on two very different fronts.

In terms of health, the use of doping substances outside of medical indication can cause serious and cumulative problems. Anabolic steroids, for example, are associated with alterations in cholesterol, liver overload, cardiovascular problems and hormonal imbalances. Excessive stimulants can cause arrhythmias, spikes in blood pressure and significant anxiety. Inappropriately used diuretics lead to dehydration and electrolyte disturbances, which can be dangerous for the heart. Growth hormone outside of a therapeutic context has already been linked to joint alterations and glucose metabolism changes.

In the sports field, a confirmed positive result usually brings temporary or even multi-year suspension, loss of medals and titles, in addition to the impact on the athlete's reputation and career, even when the case is one of unintentional use.

Why do these substances appear in the test?

When a substance enters the body, it undergoes a process of metabolism, usually in the liver, and is gradually eliminated through urine (and, to a lesser extent, through sweat and other routes). During this process, it leaves "traces": the original molecule itself and its metabolites, which are the substances resulting from this breakdown. The anti-doping test is designed precisely to identify both the substance and its metabolites in urine or blood, even at very low concentrations.

The time a substance remains detectable varies greatly: it can be from a few hours to weeks, depending on the type of substance, the dose, the person's metabolism and the route of elimination. This is why someone can "test positive for doping" even having used something days before the competition.

How is the anti-doping test performed?

The collection is accompanied by a doping control official, without prior notice to the athlete, and can occur even at home or at the training venue. The urine sample (or, in some cases, blood) is divided into two sealed vials, called sample A and sample B, and sent to a laboratory accredited by WADA.

In the laboratory, sample A first undergoes screening, checking the pH and density of the urine, followed by a stage of substance separation by chromatography (gas or liquid). Then, a mass spectrometer fragments the molecules found and compares the pattern obtained with that of substances already catalogued as prohibited. This entire process is done without the technician knowing the athlete's identity, to preserve the integrity of the result.

If the prohibited substance is identified, the laboratory performs a new confirmation analysis before officially declaring anything. Only after that is the athlete notified and can request the opening of sample B, kept frozen, for a counter-analysis. If the result is confirmed also in sample B, the case goes to trial by the responsible bodies.

What are the criteria for a result to be considered positive?

Here there is an important difference between two types of substances on the WADA list:

  • Substances with a threshold limit: only generate a positive result if they exceed a minimum concentration defined in the urine. This is the case for ephedrine (limit of 10 micrograms per millilitre), pseudoephedrine (150 mcg/mL) and cathine (5 mcg/mL), for example. Below this value, even if the substance is detected, no infraction is characterised.
  • Substances without a threshold limit: any detectable quantity is sufficient to configure an adverse result. This is the case with cocaine metabolites, various anabolic steroids and other substances considered incompatible with sport in any concentration.

For the case to actually become a confirmed violation, it is necessary that the finding of sample A be reproduced in the confirmation analysis and, when requested by the athlete, also in sample B. Only after this double-check does the process go to the bodies that will evaluate the circumstances (intentional use, contamination, unauthorised medical prescription, among others) and define the sanction.

Finally

The main point here is not to generate fear of tea or flu medicine, but rather to reinforce a simple precaution: anyone who participates in competitions with anti-doping control, even at an amateur level, should check the composition of medications, supplements and "natural" products before using them, and, whenever possible, talk to a doctor about what they are taking.

This content is for informational purposes and does not replace a medical consultation. Before using any medication or supplement, especially if you participate in sports competitions with anti-doping control, seek guidance from a healthcare professional.

Dr. Rebeca Soares Andrade CRM - GO 39335