Connection between antihistamine and endurance racing

Triathlon Forum
1

Years ago during packet pickups at a 70.3 I had some strange allergy symptoms. I chalked it up to pollen or something in the air. Long story short I did everything that I normally do before a race the only difference was that I took a Benadryl before bed. That race just so happened to be my strongest performance in any race 70.3 or 140.6 distance. I never thought much of it the thought had crossed my mind about taking the Benadryl the night before but I just attributed my performance to hard work consistent training and a good clean diet.

Fast forward a few years and I am having another day like the day I was having at packet pickup. I feel a little itchy having a hard time breathing etc. There is pollen in the air so bad that it looks like it’s snowing. I take a Benadryl again just like last time and I wake up in the morning and have an exceptionally good workout. It was a workout so good that I feel like the Benadryl must have had some impact on my performance. It is most noticeable with my breathing and also my heart rate.

Is there any connection either anecdotal or documented with taking an antihistamine and improved endurance performance?

Like I said I’ve taken two Benadryl in the past 4 years and the next day after both times I felt unstoppable during my workouts. It just seems kind of like a big coincidence.

2

Benadryl works to reduce sinus issues. If you have blocked sinuses I’d imagine it’s hard to breathe, which could have been affecting your oxygen intake/uptake. Hardly a qualified medical opinion but can easily see there being a benefit from being unblocked and able to breathe properly, if you had been suffering previously.

3

https://www.thecanadianencyclopedia.ca/en/article/laumann-fails-drug-test

Benadryl cost one Olympian. The formula changes between Canada and the US and maybe between markets. Anyway it’s use is banned.

4

https://www.thecanadianencyclopedia.ca/en/article/laumann-fails-drug-test

Benadryl cost one Olympian. The formula changes between Canada and the US and maybe between markets. Anyway it’s use is banned.

Pseudoephedrine is banned in-competition above a threshold. This threshold was instituted as a result of the above. So it’s not clear to me if taking a normal therapeutic dose the day before would trigger a positive…not sure of the pharmacology.

Benadryl with diphenhydramine is not banned in any way. That formula is most common now, I believe.

5

Not only is it relieving allergy symptoms making it easier to breathe, but it most likely contributed to a good nights sleep which is probably the largest training benefit.

6

I was curious about that so of course I asked Google, or rather Wikipedia.

In the United States and Canada, the active ingredient is diphenhydramine. In the United Kingdom, the active ingredients of Benadryl are the antihistamines acrivastine or cetirizine. Benadryl is also sold as a cough medicine in Australia and New Zealand containing diphenhydramine, as well as the antitussive dextromethorphan or the expectorant guaifenesin.

It seems that they do alter the formula in various markets, now I have no idea if the changed formula contains anything that has an effect on performance. When I googled that I got this study.

https://www.inverse.com/mind-body/antihistamines-exercise-study

Which says it hurts (if used during training), and then yet another that said something completely different, for one time use

https://faseb.onlinelibrary.wiley.com/doi/abs/10.1096/fasebj.2018.32.1_supplement.723.2

So maybe it does and maybe it doesn’t, is my own scientific conclusion…:0)

7

Benadryl is a 1st gen antihistamine meaning it crosses the blood brain barrier (BBB). That can lead to both sedation and impairment.
(I know someone who got a DWI on benadryl and lost their job - don’t be that person)

You probably had multiple effects from taking 25mg.

  1. since it crossed the BBB you slept great -yeah for sleep!
  2. It blocks histamine at the H1 receptor. if histamine isn’t blocked you can get your normal allergy symptoms such as watery eyes, sneezing, coughing, trouble breathing etc.

The one thing to look out for when taking a Benadryl is that you can have next day residuals such as being tired or groggy. You might be better off switching to a kids dose (12.5mg) or a kids dose + a 2nd gen antihistamine such as allegra, claritin, clarinex. Zyrtec can cross the BBB.

Allegra, active ingredient is fexofenadine, is the only antihistamine that does not cross the BBB. Claritin can cross at above 10mg, clarinex at dosing > 5mg, zyrtec at normal dosing.

fwiw I used to sell an antihistamine when I first became a pharma rep a few decades ago. I wrote a pretty comprehensive primer on antihistamines a long time ago on ST.

8

I’d put my money on a better nights sleep leading to better performance.

9

I’d put my money on a better nights sleep leading to better performance.

x2 - the exact same drug (diphenhydramine) is sold as a sleep aid too.

that and of course relieving allergies, which would help performance too.

10

I’d put my money on a better nights sleep leading to better performance.

x2 - the exact same drug (diphenhydramine) is sold as a sleep aid too.

Frist gen antihistamines are typically prescribed for the side effect of sleep as much, if not more often, than for their intended use.

One problem w/this one can develop a tolerance. Next thing you need 50mg of Benadryl instead of 25mg to sleep as well which can lead to next day residuals

11

Question for you, Brian, since you are obviously knowledgeable in this subject; How much pseudoephedrine (in mg), and how close time-wise to race start, crosses the threshold into being a banned dosage? I know there are many, myself included, who take some form of allergy medicine in conjunction with, or including, pseudoephedrine. Mine for example, is usually 60-120mg first thing in the morning.

12

All I know is that if I take even a partial dose of Benadryl, I’m out for 24 hours…

13

Question for you, Brian, since you are obviously knowledgeable in this subject; How much pseudoephedrine (in mg), and how close time-wise to race start, crosses the threshold into being a banned dosage? I know there are many, myself included, who take some form of allergy medicine in conjunction with, or including, pseudoephedrine. Mine for example, is usually 60-120mg first thing in the morning.

It’s been a while, but I did some research on this a few years ago because I regularly use pseudoephedrine for allergy symptoms, but wanted to “be legal” for Masters Swimming competitions. The conclusion I reached, based on the pretty low threshold to pop “ hot” if tested, was to take my last regular dose 3 days before the event, then nothing until after the event.

For those three days I was off pseudoephedrine, I used an Oxymetazoline nasal spray to control nasal congestion.

14

Question for you, Brian, since you are obviously knowledgeable in this subject; How much pseudoephedrine (in mg), and how close time-wise to race start, crosses the threshold into being a banned dosage? I know there are many, myself included, who take some form of allergy medicine in conjunction with, or including, pseudoephedrine. Mine for example, is usually 60-120mg first thing in the morning.

I’m going to quote WADA, do the half life and then give you some ideas to think about at the end of the post - although I’m going to guess a bit there.

From WADA:
Pseudoephedrine: Prohibited when its concentration in urine is greater than 150 micrograms per millilitre.

pseudoephedrine, in conjunction with a diuretic or masking agent, will be considered as an Adverse Analytical Finding (AAF) unless the Athlete has an approved Therapeutic Use Exemption (TUE) for that substance in addition to the one granted for the diuretic or masking agent.

Half life:
The half life is somewhere between 5 & 8h for pseudoephedrine. I’d use 8h when trying to figure that out for maximal safety. 120mg = 120,000 mcg. reduce that by half every 8h for absolute safety.
120,000mcg/8h=60,000mcg/8h=30,000 mcg/8h=15000mcg/8=7500mcg/8=3750/8h=1875/8h=937.5/8h=468.75/8h=234.375/8h=117.1875.

the tldr is ~3d if you go by the 8h half life. Given that most people take allergy meds more than just 1x you may want to give yourself a 4th day

Me guessing:
Since you said 60-120mg fist thing in the morning I’m going to guess you’re taking fexofenadine (allegra D/telfast D) and neither loratadine (clarition D 12h) nor cetirizine (zyrtec D). The 60mg allegra is a BID dose. hold that thought.

If that’s the case what I would do is buy a 30d supply of the fexofenadine 60mg or the once a day which is 120 or 180mg (depending where in the world you are) as well as a 30d supply of fexofenadine D which comes in a 60mg tab + has 120mg pseudoephedrine w/ it. In the morning take the Allegra D and in the evening take the 60mg or the 120/180 mg once a day dose. You can safely take more than recommended w/ fexofenadine as it doesn’t cross the BBB and there are numerous studies with > the recommended dosing with no adverse side effects. IIRC there was a case study where one person took 30d supply of the 180mg at one go.

The 3-4d before comp switch to just the once a day Allegra and add in the occasional 60mg if you’re experiencing breakthrough symptoms.

If you are on Claritin it’s sort of the same but you will want to get the 5mg dose (aka kids dose) for the evenings to help control allergy symptoms. This gives you the pseudo in the AM and then other 5mg tablet in the evening .

By dosing either this way you get the pseudoephedrine in the day and the regular dose in the PM so you can sleep.

Hope that helps

15

Thanks Brian. I am indeed taking Allegra, and adding the 60-120mg pseudoephedrine with it, making it a less expensive version of Allegra-D. I only take it in the morning, but have taken an additional 60mg pseudoephedrine later in the day if congested. It sounds like, if I take the above dosage in the days leading up to a race, and then on race day only take 60mg pseudoephedrine, I should be ok USADA-wise? If not, I’ll simply use Afrin for a few days leading up to the race.

Regards,
Craig

16

Thanks Brian. I am indeed taking Allegra, and adding the 60-120mg pseudoephedrine with it, making it a less expensive version of Allegra-D. I only take it in the morning, but have taken an additional 60mg pseudoephedrine later in the day if congested. It sounds like, if I take the above dosage in the days leading up to a race, and then on race day only take 60mg pseudoephedrine, I should be ok USADA-wise? If not, I’ll simply use Afrin for a few days leading up to the race.

Regards,
Craig

No do not take Afrin. That will quite often cause rebound. Use a nasal spray like flonase or nasacort aq.

Stop the pseudoephedrine 3-4d prior to the race and continue the antihistamine.

17

Gotcha. Thanks.

18

No do not take Afrin. That will quite often cause rebound. Use a nasal spray like flonase or nasacort aq.

Stop the pseudoephedrine 3-4d prior to the race and continue the antihistamine.

I use Flonase and Zyrtec daily for “base control,” and pseudoephedrine when needed (and not in competition) to manage seasonal flares. I’m aware of the rebound effect of Oxymetazoline, but have found that using it sparingly for 3 days, when pseudoephedrine isn’t an option, to be effective. If possible, I try to only use it only on race day, shortly before the event. YMMV.

19

All I know is that if I take even a partial dose of Benadryl, I’m out for 24 hours…

Same. If I took one the night before a race, I probably wouldn’t make it to the starting line.

20

All I know is that if I take even a partial dose of Benadryl, I’m out for 24 hours…

Many years ago at a race where a bunch of STers were racing and we were talking smack going into the half, one of us took something and missed the start.

He finally made it to the race about the time I was looping past transition area about 5 miles into the run.