Safe to combine antihistamines for hay fever?

Any pharmacists out there? I get rampant hay fever and the modern one-a-day ceterizines and loretadines seem to be almost ineffective. Piriton Allergy [chlorphenamine maleate every 4 hrs] does work but is drowsiness-inducing hence not good for driving. If I have already taken a cetirizine can I take a Piriton later or will I need to wait 24hrs? How about a cetirizine early morning and a Piriton at 6pm, at my worst time for sneezing? Or will my nose explode and my entrails fall out?
Any help appreciated. BTW Phenylephrine doesn't help either.

Don't worry, I am going to check with a pharmacist before combining. Just looking for ideas and others' experience, no go areas etc. Thanks for your contributions so far.

I use Singulair once a day, Benadryl once a day, and if needed, Claritin once a day, and sometimes a hit of Advair. I never got sick, but I am no expert, so talk to a pharmacist and see an allergist if you can't get away from what is irritating you.

I am a pharmacist and it would be okay to combine the two. Chlorphenamine will cause a little bit of drowisiness but the ceterizine shouldn't cause much if any. Report It

ring nhs direct I would never take medical advice here

I have severe allergies and take Singulair, Allegra and Flonase. You can take both meds but I wouldnt do it too frequently. Antihistamines can cause an accelarated heart rate, which could result in sudden death if you're consuming alot of caffeine and antihistamines or other meds. Although I've worked in the medical field, I'm not a physician and would strongly recommend speaking with a pharmacist or your primary physician. Also, try Zyrtec.

The best way is to avoid the allergen ,the alternative is u can use antihistaminics belonging to fourth generation,since they r effective &non sedative like Promethazine.U can take cetrizine & chlorphenamine at a time,beware of its sedation.