It is springtime and allergens are thickening the air, so I should do my obligatory mention of:
Cromolyn sodium spray. Brand name: Nasalcrom.
Bane of the gods of pollen:
It stops the nose's mast cells from releasing histamines in the first place . No (or far fewer) histamines= no need for antihistamines = an efficient and focused medicine.
Inexpensive:It is over-the-counter in the US--it used to be a prescription-- and costs about $10 for a 3-6 month supply for me (generic at Kaiser), or $16-$20 for the brand name at Walgreens.
The 3-6 months depends on how long the 200 metered doses last-- I usually start at 3x/day (6 doses), and then maintain at 1x/day (2 doses). But if the allergens are particularly bad I'll use it more often.
Not a steroid spray = no rebound effect, even if it looks like them / gets shelved with them
It often is shelved with / gets confused with steroid sprays--the kind you can't use for more than 3 days without a bad rebound effect. It isn't a steroid. It builds up over a day or two of use, and it also fades away slowly-- great for when you forget it on a trip, because you're not instantly in trouble.
I've also used cromolyn eyedrops (found in Ontario pharmacies--not seen in California, for whatever reason), and that's useful too.
Consider mentioning it to your local allergy sufferer.
It is a sadly unknown medicine, given its benefits. Of course it's not going to work for everyone, but I find far, far more people have never heard of it than have tried it and found it to not work, when the topic of pollen allergies comes up.
Research Notes
According to RXlist, the nasal solution's most common side effects are sneezing or nasal stinging--I get that at the start, although it fades quickly as I get used to the spray each spring. A rare side effect mentioned is nosebleeds: one commenter below got them.
It also says for "perennial allergic rhinitis" it may take 2+ weeks for the effects to become apparent, and they note one can keep taking anithistamines and/or decongestants while waiting. It also works best if you start it before exposure to the allergen.