Medication causing a false negative test

[Babydontcry]

Has anyone any experience of diphenhydramine causing false negative pregnancy tests?

Bumping with hope

I haven't taken that antihistamine around the time I would have done a pregnancy test, so no experience, but it seems extremely unlikely to me. Taking antihistamines around ovulation might make it slightly less likely you'd get pregnant in the first place (because they dry up your CM), but what mechanism would cause them to produce a negative pregnancy test? To maintain a pregnancy you need to be producing HCG, and so you could only be actually pregnant but not testing as pregnant if the drug somehow caused HCG to disappear from your urine. But I can't imagine how that would happen!

Thanks Hops for replying. I read on the boots test leaflet that certain allergy tablets can, but I've googled and nothing else is coming up stating this is an issue. AF is unusually two days late so guess I will test again in a few days if still no sign!