Its a difficult question to answer as every person is a little different as mast cells can affect any part of the body. I have a dx of MCAS, which was obvious because a dose of doxycycline kicked off 24 hr a day body wide itching with no rash 19 months ago now. But my background was one of MCS for many years. I had also had a lot of breathing problems that weren't fixed by my asthma meds and had everyone scratching their heads.
I had always been sensitive to perfumes, chemicals etc, but after the doxy I was now reacting with throat tightening and increased itching and fatigue with foods, newspaper and magazine print and food being cooked. I couldn ttolerate and med without severe increased itching, including just a paracetomol for pain, or herbs or most supplements. My sense of smell became VERY acute and anything I could smell I was sure to be reacting to with generally worsened health.
My breathing problems put me in bed for a good 3 -4 months as I could do nothing but lay or sit and try and breathe it was hell, yet no one thought of MCAS.
Eventually I tracked the dx down myself and saw a private specialist here in the UK 9there are only 2 or 3 in the UK who can dx this)
My Tryptase is normal, had no other tests, dx was clinical.
Was prescribed H1 up to 4 times a day (actually cant tolerate any more than twice a day). This controlled some of the itching, but my reflux (another symptoms) was out of control again - I didn't know this was also mast cells, but was given an H2, ranitidine twice a day. Now my reflux and some itching were controlled, but the itching would break through severely for weeks at a time. So we played around with different antihistamines. Some would work but often I have terrible and rare side effects to medication. Fexofenadine gave me severe suicidal depression - but hey I wasn't itching - great! Ceteirizine worked, then stopped working, double dose put me to sleep.
Loratidine mainly works I take two a day, but if I take three I get heart palpitations so I may actually be reacting to the meds that help us and here in the UK there are no compounding meds and my GP tells me the nHS wouldn't pay for this anyway.
I have also had a seizure as a result of trying a new drug and I now know this was an anaphylactic reaction.
A couple of months ago my GP reluctantly agreed to add in Ketotifen - but it is very sedating so I can only take a small amount at night. At first it was like a miracle drug. Itching stopped and I had more energy and a lot less fatigue. When I tried to up the dose the itching got worse, so again ccould be reacting to fillers in the meds. I am now on half a tab once a day - cant take more as it doesn't help.
I had about 4 great weeks where I thought we had found a big answer to my ill health. Was up cooking, cleaning, going out more (still with wheelchair, but at times pushing ti and walking a little). Then I crashed very badly and now am right back to square one with being bedbound for most fo the day and entirely housebound again.