Though they each try to get your symptoms under control, they do it by different mechanisms which when taken altogether, can work even better than by itself.
So, using the table below, a patient can generally take one medication from each column at the same time (but not more than one medication contained within a column unless directed by your doctor). For example (highlighted in BOLD ), a patient can choose to take allegra, nasonex, singulair, patanase, nasalcrom, and saline flushes all at the same time.
Steroid Nasal Spray
Anti-Histamine Nasal Spray
Cromolyn Nasal Spray
Seven hundred and twenty (720) patients 3 to 11 years of age with allergic rhinitis were treated with mometasone furoate nasal spray, 50 mcg (100 mcg total daily dose) in controlled clinical trials (see CLINICAL PHARMACOLOGY, Clinical Studies section). Twenty-eight (28) patients 2 to 5 years of age with allergic rhinitis were treated with mometasone furoate nasal spray, 50 mcg (100 mcg total daily dose) in a controlled trial to evaluate safety (see CLINICAL PHARMACOLOGY, Pharmacokinetics section). Safety and effectiveness in children less than 2 years of age with allergic rhinitis and in children less than 18 years of age with nasal polyps have not been established.
Corticosteroids have been used as drug treatment for some time. Lewis Sarett of Merck & Co. was the first to synthesize cortisone, using a complicated 36-step process that started with deoxycholic acid, which was extracted from ox bile .  The low efficiency of converting deoxycholic acid into cortisone led to a cost of US $200 per gram. Russell Marker , at Syntex , discovered a much cheaper and more convenient starting material, diosgenin from wild Mexican yams . His conversion of diosgenin into progesterone by a four-step process now known as Marker degradation was an important step in mass production of all steroidal hormones, including cortisone and chemicals used in hormonal contraception .  In 1952, . Peterson and . Murray of Upjohn developed a process that used Rhizopus mold to oxidize progesterone into a compound that was readily converted to cortisone.  The ability to cheaply synthesize large quantities of cortisone from the diosgenin in yams resulted in a rapid drop in price to US $6 per gram, falling to $ per gram by 1980. Percy Julian's research also aided progress in the field.  The exact nature of cortisone's anti-inflammatory action remained a mystery for years after, however, until the leukocyte adhesion cascade and the role of phospholipase A2 in the production of prostaglandins and leukotrienes was fully understood in the early 1980s.