My training has been super solid this year but performance has been consistently weaker than last season despite very similar diet, routines and so. For example, FTP is sitting at 310-315 rather than 320-330 and 5, 10 & 20 minute power is off by a similar percentage.
One thing that occurs to me is that last August - per my GPs advice - I started taking Phenergan at night to get to sleep. I’ve used it religiously since then as having a night off is a recipe for no sleep. I know there’s something not-quite-right about it but the GP assures me it’s safe and I’ve just continued as it works so well.
Starting last night I will give the Phenergan a break and let’s see if anything changes over the next block. I will be a bit sleep-deprived for a few nights but happy to give it a go.
Does anyone else have experience with long-term antihistamine use having an impact on performance?
If you don’t need the antihistamine to combat allergies there are other options to help with sleep. Personally I’m prescribed Propavan with positive results. If you’re concerned you should talk to your doctor.
Thanks for the responses folks. That study did have quite high dosages but I am just struggling to find something that explains the performance dip. I will report back on how I go after 4-6 weeks off the meds.
Also thank you for suggesting melatonin and Propavan. I will take a look if I can’t get my sleep back on track with good hygiene.
It’s been a few years now but did getting off the allergy meds help with performance? I quit taking allergy medication after I saw that study and am starting to feel like I’d be better off back on it.
I remember when this was covered on the podcast years ago (around the time of @Nate_Pearson having major sinus issues). I guess it depends on the allergies, but I took the view my training would be more impacted by not taking the antihistamines than by maybe blunting some adaptations. But that maybe n=1. Before the antihistamines, I generally had several doses of full on sinusitis a year, much worse skin allergies that affected my sleep - all proven to affect my training!
they gave participants a f-ton of antihistamines in the study. If I recall, it was equivalent to 3 otc allegra/claritin like antihistamines right before the work out. They also gave them more than normal H2 blockers if memory serves. Who knows what the results would have been had they given them 1 claritin and no h2 blocker?
They didn’t study people with allergies, if I remember correctly. So yes, if a person without allergies takes a ton of them, it led to less improvement. We cannot extrapolate that to reduced performance if you have allergies, however. Maybe for someone with allergies, taking an antihistamine reduces levels of histamines in the body to the “correct” levels?
Here’s a link to the full paper. You have to jump way down to the methods section to find the histamine blockers used and their dosages. They were fexofenadine 540 mg (H1) and 300 mg of ranitidine or 40 mg of famotidine (H2). H1 means allergy-type antihistamine and H2 means stomach acid reducer, like Pepcid.
Fexofenadine is Allegra, which has a usual 24h dose of 180 mg; the study used a triple dose.
Famotidine is Zantac 360 and Pepcid AC, which has a original strength does of 10 mg or Maximum Strength dose of 20 mg; the study used a double to quadruple dose.
In this study were trying to completely block the reception of H1 and H2 histamines by the receptors to see if histamines play a role or not in training adaptations. So the dosages they used make sense. The study concludes that they do and that the effect is significant. I don’t see an obvious reason to dispute that.
What isn’t answered in the study is whether the typical dosage of these medications will have a significant impact on those adaptations. That needs another study.
Whether the study subjects were experiencing allergies and too what extent, isn’t relevant to the study that was done. That would affect histamine production, but they turned off reception. If no histamine can interact, it doesn’t matter how much exists. Which was the right thing for their study intent, but doesn’t give us the answers we want as cyclists.
It’s “Telfast” here in Ireland, and prescription only at 180mg (120mg is over the counter in the last couple of years). Loratidine and Cetirizine are the two more common over the counter (the latter worked better for me, but still not as well as fexofenadine).
I agree with everything you said. I was in no way trying to argue the methods or that results of the study are incorrect, simply that the results might not apply to a cyclist with allergies taking 1 or even 2 antihistamines a day during certain times of the year.
Probably whatever reason you need to take an antihistamine to even sleep has to do with your performance decrease. Not the antihistamine itself
You’re saying I can’t sleep because of X so I take drug Y. You think drug Y is why your performance is bad. I’m suggesting it’s probably because of X that your performance is bad
I don’t think the exact medication matters for the purposes of this study. I mentioned them to show what the usual dose is and compare to the studied dose, to show that they went pretty high on some of the doses.
Would the normal dose also reduce training adaptations? It seems very likely it would. But by how much? We don’t know that it’s a linear relationship or not.
With Loratidine and Cetirizine I would expect similar trends due to them also being H1 antihistamines.
I am the OP and am really interested to read these new posts after a few years.
In August 2021 I stopped taking Phenergan (25 mg at night) and found that my power did bounce back in the next block. I can’t say if it was a cause and effect relationship there.
My sleep was garbage again though and so I started back on Phenergan but at a lower dose (10 mg and later 5 mg). Sleep is plentiful and high quality and power is same now as pre-Phenergan.
I have to say though - reading xortle’s link about regular use of anticholinergic drugs potentially increasing the risk of dementia made me stop in my tracks and I will go back to my doctor to discuss those risks and other options.
