I've had diagnosed allergies since age 11, to all kinds of things, some of which I can avoid (cats) and some of which I can't (dust). I am sure an allergist will review all the options with your wife, but a few thoughts:
Things that work:
1. 10 years of allergy shots reduced my dog and ragweed allergies to not being allergic anymore
2. daily Zyrtec (aka Cetirizine) (Claritin does nothing for me, neither does Benadryl), but Zyrtec has been my holy grail, and I have no side effects; I probably tried every prescription and OTC allergy med there was between 1991 until Zyrtec came out by Rx only. I happily paid the high price and am now even happier now that it's generic. Maybe your wife just needs to try more options.
3. daily Fluticasone aka Flonase nasal spray (I have an Rx but they sell it OTC). I was having pretty severe allergies (main concern being my itchy/watery eyes) last fall and saw my doctor, and she recommended the nasal spray. I was like, "Nasal spray for my EYES?" and she said yes, and that
I could do two sprays in each nostril TWICE per day while things were bad. I was skeptical but tried it, and what do you know, it worked. Not having the nasal reaction totally stopped the itchy eyes. Also, I have kept up with it and I haven't gotten sick all winter. This may be the preventative cure for the common cold.
4. When I'm sick or having especially bad nasal congestion, I use the NeilMed sinus rinse:
http://shop.neilmed.com/Sinus-Rinse/b/9814764011 It's just a bottle and a little packet of solution to neutralize the water you put in the bottle, and you squirt it through your sinuses, same principle as a neti pot but easier to use. It cleans everything out. During high pollen season, this can be helpful.
I also shower at night so I get all the day's dust/pollen off of me before getting into bed. This seems to help me a lot.
5. Albuterol inhaler for asthma-like reactions. I only need this when I've been around a cat. It's an awful feeling, and I hate using it since it makes me jittery, but sometimes it's the only thing that works to get my airway to open and stop coughing.
Things that I hate:
1. People who insist their cats are "clean" or that their house is "clean" from cat dander. Sorry, I can tell if your house had a cat in it at some point, even if you haven't had a cat for years. The best way to avoid
allergies is avoid
allergens, so if there's anything your wife can do to avoid what she's allergic to, do it.
2. If I complain about allergies or ask if someone has a cat, I hate it when people say "do you take allergy medication?" I usually try preempt this by saying, "I'm allergic to ___ and take daily allergy medication" to stem this, but I don't want to get into a health history with most people.
Good luck!