My POTs had got really bad again the other week and I had been noticing on rainy/humid/thunderstormy days it was really bad and wondering if this was due to allergies/increased histamine release? I had 3 really bad days and ended up in Emergency and asked to be tested for mast cell disease. I tried the Darier’s sign test at home as suggested by Dr Diana and on rubbing my skin it came up a really bright red colour and stayed there for around 20 minutes and I actually wrote my name across my chest with my finger (this has now reduced significantly since being on antihistamines). The doctor said he thought it was pointless testing for mast cell disorders when the treatment would be antihistamines anyhow, so he put me on 3 different types- Zantac, Polaramine and Phenergan and I’ve been on antihistamines for 2 weeks now and so much better already! I take the Zantac twice a day and the other ones when I feel I need to (being a bit careful as I’m breastfeeding). I can now go and do the shopping for a couple hours before I need to go lay down as opposed to lasting 30 minutes or less as previously. I am able to do a lot more and don’t feel like my neck is as swollen and it’s much easier to breathe, less fatigue etc.I always found an antihistamine helped when my symptoms got really bad (the doctor put me on them as he thought I was having bad asthma when I first started having problems so always knew they helped, but wasn’t sure why). I would officially like to be tested though so I definitely know this is the problem. I think it possibly is as when I get really bad I get flushing symptoms and my bp can go high (as well as low) and I get the postural tachycardia and are very sensitive to beta-adrenergic medications eg. asthma puffers like Symbicort. I also get random bouts of diarrhoea and recurrent sinusitis,asthma symptoms, neck feels swollen, get breathless, wheeze sometimes all with the POTS symptoms. Does anyone else have similar? Are there other tests you can do for mast cell problems?