Junior dos Santos apparently tests positive for hydrochlorothiazide - what is that?

Junior dos Santos apparently tested positive for banned diuretic hydrochlorothiazide. Iain Kidd explains what that is, why athletes might use it, and whether this could have an innocent explanation.

An out-of-competition sample taken from Junior dos Santos on August 10th came back with a result causing him to be pulled from his bout with Francis Ngannou at UFC 215 in September. Junior’s manager

Junior’s manager released the following statement to MMA Junkie, saying the result came back positive for a banned diuretic called hydrochlorothiazide:

“Junior tested positive for a substance called Hydrochlorothiazide, which is a diuretic and is banned by USADA due to its use as a masking agent. We do not know where this substance came from. Junior has had his blood and urine randomnly tested many times and has never once tested positive for a banned substance.

We requested testing of his B sample today. Most times, the B sample will show the identical results as the A sample. Therefore, we are already working on analyzing his nutritional supplements and medications to determine whether anything might have been contaminated. Jeff Novitzky and Donna Marcolini of the UFC have provided the guidance for this process, and we are grateful to them for their professionalism and competence.”

So what, exactly, is hydrochlorothiazide (HCTZ)? HCTZ is a thiazide-class diuretic, most commonly prescribed as a first-line treatment of high blood pressure (hypertension). It is banned by WADA because of its potential use as a masking agent, as are basically all other diuretics.

While there are different classes of diuretic with different mechanisms of action, the end result tends to be more or less the same; the person taking them will expel more fluid via urination than usual. In theory this means the urine that is produced will be more diluted, which could make detection of banned substances in that urine more difficult, especially for substances with detection/decision thresholds.

Hydrochlorothiazide is known to show up, unlabelled, in supplements, as most recently happened to UFC athlete Guido Cannetti, who had his suspension reduced when USADA testing on both opened and sealed batches of a supplement showed they contained banned substances, including HCTZ, which were not present on the label.

Hydrochlorothiazide has also been shown to turn up in medications like non-steroidal anti-inflammatories which are completely legal and purchased in pharmacies. Even if companies follow the industry standard 10 parts-per-million allowed contamination, that’s still enough to cause a false positive for hydrochlorothiazide.

What this means is, it’s possible for an athlete to buy some ibuprofen over the counter from a pharmacy, and for that ibuprofen to, legally, contain a tiny amount of leftover hydrochlorothiazide. An amount not enough to have any physical effects, but still enough to show up on a drug test.

We don’t know what kind of levels of hydrochlorothiazide JDS’ test came back with yet, but it’s worth noting that contamination of both supplements and unbanned medications with HCTZ are not exactly unheard of.