If you think hayfever/pollen allergies are making your asthma worse whilst pg then kick off to get them to prescribe Piriton. Ask to see a consultant if your GP can't/won't prescribe.
Long story but I have asthma and was also smoking when I got PG. I stopped smoking and went onto patches with the support of the stop smoking midwife. After 5 days of not smoking, rather than feeling better I felt horrendous. Asthma was awful (got that dry, tickly cough all night), chest tight and wheezy, and had streaming nose and eyes and couldn't stop sneezing long enough to string a sentance together. Because of the trauma my poor nose was suffering I also got a nose, then lips full of coldsores.
I was a mess. After speaking to practise M/W, practise nurse then seeing GP at doctors, all who said I couldn't have any anti-histamanes my stop smoking M/W asked me what I was going to do. Told her I would start smoking again (all symptoms triggered by stopping smoking). She had seen the state of me and agreed I couldn't continue in that state all through the summer and we were both concerned that if the asthma got much worse I would end up in a big mess.
She spoke to a consultant at the local hospital. He laughed and told her to tell me to take the recommended adults dose of piriton until it was under control, then drop it down a little. I was about 8 weeks at the time so still in the first trimester.
Was much better within hours lol.
GP's don't like prescribing anything to PG women as most things are not tested on PG women and they are terrified of being sued. But Piriton has been around for many years and from my research on the web no adverse affects have ever been reported when used by PG women. Of course we have to calculate any risk when taking any medication. In my case it really was Pirtion vs Smoking and Piriton won hands down. Even before I smoked my asthma was always much worse in summer. They don't like giving oral steriods whilst PG and I had those quite a lot to sort out attacks in the past. Without the steriods I think I would have ended up being in hospital on a few occasions. And a lack of oxygen can't be good for baby either.