Antihistamines and prolonged QT interval

[Scrabblefiend]

As the hay fever season approaches, I asked my GP if there are any interactions between my medications and antihistamines. He returned to last year’s ECG which showed AF happening, and pointed out the prolonged QT interval and explained a bit more about what that means (I hadn’t understood it at all and all the focus has been on my AF). The upshot is that antihistamines can affect the QT interval and I should use them with care. Just wondering if anyone has experience of this particular interaction, one I hadn’t known about at all?

[JaneFinn]

That’s interesting, Scrabblefiend, I was not aware there was a link with current antihistamines on the market.

About 36 years ago I was on daily Triludan (antihistamine) for general allergies and my GP said no harm taking one a day permanently. Then my friend (18years old) took Triludan for hayfever which gave her sudden dangerous arrhythmia - luckily her life was saved as she was visiting her sister in hospital at the time. Subsequent tests showed Triludan can cause Long QT syndrome, and it was taken hastily off the market. I thought they were all safe now

With some meds we are advised not to drink grapefruit juice with them or can cause Long QT. I’ll be interested to hear if anyone knows of any issues with current antihistamines. Did your GP imply all antihistamines can potentially affect it? X

[Scrabblefiend in reply to JaneFinn]

Ah, I am old enough to remember Triludan. I hadn’t realised it was taken off the market - wow. The GP suggested that there’s a general risk with antihistamines still but he has prescribed Fexofenadine. It hasn’t arrived yet but from a bit of googling it looks like it is also known to affect heart rhythm, but as it says don’t use without the GP involved I guess I am safe…

[JaneFinn in reply to Scrabblefiend]

Hmm yes, it’s hard when so many meds seem to have a possible arrhythmia risk, isn’t it? Especially as we are all different in our responses too! I meant to ask my EP about my antihistamines but forgot when I saw him. He did say he was happy me taking Montelukast (in my case for mast cell activation /inflammatory response).

I hope you get on well with fexofenadine, do let us know x

[Lizziedoodle89 in reply to Scrabblefiend]

I don't take any anthistamines now as can affect af

[Rosemaryb1349]

This is very interesting to me as I recently asked on here which antihistamine was safe to take with my CCBs etc etc . I was in Cyprus at the time looking after my daughter who was recovering from a second operation and I developed an allergic reaction (itchy raised spots) all over my back. I found a packet of Boots own brand containing loratadine and started with the 1 tablet a day until after I returned to the UK. Almost immediately upon return my previously predictable Afib went into overdrive and after a 5 day long episode I was finally advised by phone by a cardiologist to double my dose of CCB and I have now received an urgent appointment for the end of April. The new dosage has gradually brought the heart rate down and the fibrillation under control but hasn't stopped another episode last night. I will have several questions for my cardiologist.

[JaneFinn in reply to Rosemaryb1349]

Oh I’m sorry to hear that - and I’ll be very interested to hear what your cardiologist says. Please do let us know! I thought loratadine to be one of the very safe ones - but maybe all antihistamines (and many meds) carry some arrhythmia risk for some people?

[hausjac]

It seems so many drugs can interact with heart medications as well. I take Disopyramide and it causes QT prolongation with most anti-emetics which is a nuisance when like me i'm having trouble with nausea due to newly diagnosed cancer. Certain antihistamines and fungicides also cause problems as well. One has to tread very carefully when taking tablets nowadays!

[Buffafly]

This morning I was sent info from the BHF re antihistamines. It takes too long to get permission for the link so I’m summarising.

Steroid nasal sprays are ok if you stick to the correct dosage.

Loratidine and cetirizine are ok. Piriton (chlorphenamine) tends to cause drowsiness so use with care. Fexofenadine should only be used if prescribed by a doctor because it can cause irregular HB or tachycardia.

Decongestant meds should not be used without discussion with a pharmacist or doctor. Look for the word ‘pseudoephedrine’ because it can cause tachycardia, high BP and palpitations.

Hope that helps.

[Scrabblefiend in reply to Buffafly]

Yes I got that alert too! Clearly a timely question