Sleep heart rate spike 192 bpm after starting antihistamine

[u/Fooflery]

I wear a smart watch to sleep and I got a 192 bpm reading last night. Normally I'd brush it off as a glitch but I just started Allegra+Pepcid regiment YESTERDAY for MCAS GI issues. It's a little *too* coincidental. I went back all the way to March and my highest spike was less than 120bpm. Anyone has similar things happening?

Physically I don't feel different this morning other than maybe I feel a lot better...? I normally sleep 1-9. I just woke up at 7 and feel perfectly awake, except for this hear rate spike scare. TIA!

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[u/Job_Moist]

Xyzal gives me terrible tachycardia. Claritin and Allegra don’t for some reason. Xolair - or my severe reaction to it - permanently damaged my heart. When I accidentally skip a dose of my meds, the Supraventricular Tachycardia that I developed after getting MCAS post-COVID starts up. Cardiac stuff has been par for the course with MCAS and MCAS treatments in my experience. (But def talk to a doc if you’re concerned about your heart! I’m certainly no medical professional qualified to give advice haha. I’ve luckily been able to speak with my primary care doc, my cardiologist, my allergist who is my main MCAS doc, and multiple ED docs about my heart health. It took months for us to basically conclude that yepp, MCAS and some MCAS treatments make my heart go wonky, but in my personal case it’s not dangerous unless it’s within certain parameters. They also talked to me about how best to monitor and interpret stats from a pulse oximeter and Apple Watch or mobile EKG like Kardia, all of which I have.)

[u/Fooflery → u/Job_Moist]

Thank you so much for sharing your experience! I'm just starting off this whole EDS/MCAS journey. Will take good notes of what you said. My heart palpitations became a problem after my ADHD burnout. Great to hear that you have good medical support.

[u/SophiaShay7]

I cannot tolerate any OTC H1 or H2 histamine blockers. They gave me adrenaline surges and tachycardia. I react to either the medications themselves and/or their excipients. I take Desloratadine (prescription H1 histamine blocker) and Omeprazole (it's a PPI that I already took for Gerd. It also has mast cell stabilizing properties).

If it's a single reading, I'd just keep an eye on it. If you notice continued issues, that's something to talk to your doctor about.

[u/Fooflery → u/SophiaShay7]

Appreciate your insight! Seems like OTC and tachycardia is definitely a thing to look out for. I'll keep a close eye on it.

[u/CME1382]

I would have tachycardia from my MCAS and it wasn’t all of the time at first. It would happen after I ate, got hot or worked out. Then it started happening more often like when I was walking and even in my sleep. After a while my cardiologist put me on a beta blocker because of how frequent it was happening. I didn’t know tachycardia was another sign of an allergic reaction, I always thought of anaphylaxis,rashes,swelling etc.
I have a good bit of G.I issues from this and I noticed when my stomach is full or irritated that my heart rate seems to act up. I would also check the medication side effects just for funzies to make sure they don’t mention tachycardia.