As is the case with many natural health approaches, know that what may provide immediate temporary relief from an allergy attack, such as a botanical, may not be the most suitable long-term solution for resolving the issue...(such as addressing your gut, your liver, or your adrenal glands.)
1. DDS-1 Probiotics with Bifidobacterium
I have used these strains of probiotics ever since starting as a nutritional practitioner in 1993 to quickly and effectively reduce histaminic responses like those described above. Like different dogs, though they may be the same species, different strains of probiotics can vary greatly in their attributes. I have repeatedly found that for histaminic seasonal allergies, the DDS-1 strain of Lactobacillus acidophilus combined with Bifidobacterium is the most effective. Recently we had the good fortune of being able to add this product to our Optimum Health Vitamins line of supplements.
As long as your stomach is empty, taking 3 of the Opti-Elite Probiotics can produce amazingly quick relief. To increase the speed with which relief ensues, I chew at least one of the capsules before swallowing to get some of the powder into my mouth, particularly under my tongue. At times this can get your sinuses to drain within minutes. (This can also be used preventatively if you know you are going to do something that is likely to provoke an allergic response...like mowing the lawn.)
Laughed at for years by established scientists, (some of whom used to come into the stores to scoff), the volumes of evidence on the benefits of probiotics for immune function now speak for themselves, and point to the systemic anti-inflammatory effects that are exerted when probiotics bind with receptors in the GI tract, helping among many other effects, to reduce reactivity. They are thought to help shift immunity from more reactive Th2-type to less reactive Th1...this is discussed below. 
For a more detailed discussion of the mechanisms at work with probiotics, see the following article.
Related article: What Do Probiotic Supplements Do For Allergies?
Also, as we discussed in last month's article, How To Improve Liver Health For Enhanced Vitality & Better Digestion, probiotics can help your liver with its detoxification goals, i.e. to escort toxins out of the body through the colon. When the wrong bacteria predominate in your gut, the toxins sent for elimination are more likely to get reabsorbed, creating an increased liver burden. Given that one of the liver's primary duties, among many, is to break down histamine, if the liver is overloaded, congested, or inflamed it is not going to perform this task as effectively.  The result is increased histamine levels, which are aggravated in the spring, and do not drop as they are supposed to making allergies worse. By reducing recycled toxins, probiotics help prevent liver-overload, allowing it to function normally and clear this histamine.
Additionally, though not commonly recognized for it, a herb which is also very supportive of liver function and has anti-histaminic properties is resveratrol. 
2. Optimized Resveratrol
Designed with allergies in mind, this formula has quickly become popular in the springtime for sufferers. It contains the following botanicals: Resveratrol, Quercetin, Nettle root, Grapeseed Extract, Pomegranate, Acai.
Optimized Resveratrol supplies a broad spectrum of antioxidant and anti-inflammatory polyphenols (i.e. flavanols and anthocyanins), shown to decrease production of inflammatory compounds associated with allergy and asthma.  Resveratrol has been specifically shown to decrease human mast cell degranulation, which reduces histamine release. In fact it worked better than the drug it was trialed against.  Quercetin is probably the best known and researched flavanol, not only for inhibition of allergies, asthma, and lowering production of histamine, but also for a huge spectrum of other immune and inflammatory modulating effects.  Nettle has also been shown to posess anti-allergy effects by blocking histamine receptors and preventing release of histamine and the associated downstream inflammatory molecules.  The root is rich in sterols that moderate immune balance by keeping the TH1/Th2 immune divisions in-check. Grape Seed Extract rich in OPC's, along with Pomegranate and Acai round-out the formula, being an abundant source of polyphenols with various flavones, flavanols, and proanthocyanidins which have been shown to increase tissue and mucosal integrity, and moderate reactivity , , , .
To relieve allergies you can either modify what happens after the immune response has already started, (for example, by decreasing histamine), or alternatively you can prevent the immune response from being mounted in the first place. This is by by modifying your immune reactivity or "tolerance".
Of course, you want the immune system to attack genuine threats, but not to over- react to things which would other wise be harmless. For this the immune system requires balance. This means balance between cell-mediated immunity, (loosely classed as Th1), and antibody-mediated immunity, (Th2).
Something I have seen work incredibly well for reducing reactivity in this regard is Ecomer TM. As covered in this past Ecomer article the alkylglerols in Ecomer™ can create a shift in immunity away from the more reactive Th2-type immune responses, (responsible for such conditions as allergies, asthma, excema, hives, etc.), toward less inflammatory cell-mediated immunity, termed Th1. 
Especially for those people who seem to "react to everything", I would recommend 2 capsules 3x per day, for 3 days, then down to 2 morning and 2 evening for a couple of weeks. Afterwards 1 or 2 caps per day will likely suffice.
Other nutrients that can help maintain this balance to promote appropriate immune responses are Vitamin D and Vitamin A. (Increased exposure to sunshine is presumably one of the reasons allergies tend to decline in the summer as Vitamin D status improves.) But I have to say that I think that the alkylglycerols in Ecomer TM are a hidden gem when it comes to reducing inflammation and reactivity from an over-active immune system!
4. Vitamins and Minerals
Pantothenic Acid, Vitamin C, and Magnesium
These three nutrients are the classics for seasonal allergies. Both Magnesium and Vitamin C have a stabilizing effect on mast cells, reducing degranulation and release of histamine, and all three have a supportive effect on our adrenal glands, particularly Pantothenic acid.
Supporting adrenal gland function maintains energy production, and one of the main reasons for this is because the adrenals produce several highly anti-inflammatory hormones, such as cortisol, adrenaline, and nor-adrenaline. In turn, reducing inflammation allows energy production to proceed normally, and the mitochondria keeps producing ATP.
We then remain unaffected and continue on with our day, without the inflammatory symptoms that accompany allergies. Particularly pantothenic acid has been popularized for seasonal allergies, and many find it helps in the range of 500-600 mg, one to three times per day. (Keep in mind there is no established upper limit, and pantothenic acid is also widely available in a healthy diet.)
For a noticeable effect from Vitamin C, I would use 2-4000 mg spread throughout the day, but be sure to use a product that contains bioflavonoids for better results. In fact, they may be just as, or more important for this application than the vitamin C itself. This was the rational behind our More Than C formula.
As for Magnesium, I would suggest 400-1000mg per day, but this intake can be limited by bowel tolerance, given magnesium's tendency to cause loose stools or diarrhea. People vary widely in their sensitivity, so you may need to experiment. But increase slowly, unless you don't mind spending a lot of time in the washroom!
Related article: Maximize Vitamin C Benefits: Key Substances To Achieve This
5. Opti-Liv Extra and Opti-Colon Cleanse
Clean up your liver, and flush those backed-up bowels
Often regarded as the most important organ when it comes to allergies and excessive reactivity, the liver's detoxification systems, (especially Phase I), can be a huge source of oxidative stress, particularly if it is not working efficiently to properly detoxify and clear toxins.
As discussed above, if the liver is stressed and the "gears are smoking" this obviously can create a lot of obnoxious, inflammatory compounds, including higher histamine which our immune system then responds to creating more inflammation....then reactivity and fatigue ensue.
On top of this, if the bowel is backed-up, what do you think this does to the liver?...Puts even more stress on it, which creates more oxidation and inflammation, and round and around we go!
On the other hand, I have counselled people who have experienced immediate reductions in reactivity from either flushing their bowel...(not a big surprise)...or from taking liver support products like Opti Liv Extra.
This formula contains ingredients that increase production of glutathione, so critical for liver detoxification, particularly to help you package-up toxins to be escorted out of the body, (i.e.Phase II Liver detox).
6. Something we've seen work for hives...Molkosan
A fermented whey culture of (L+) lactic acid.
Don't let the word "whey" scare you here if you are allergic to dairy. This product can actually improve dairy and other allergies. It is a highly purified extract of lactic acid so important for the health of the probiotic populations of your intestines. But I have to say, the results we have observed with this product go far beyond the typical explanations of it promoting proper intestinal pH.
My guess is that it directly sensitizes receptors in the gut, which then exert downstream anti-inflammatory effects....sometimes surprisingly quickly! For example, one of the problems I have not found easy to produce results for is urticaria, or hives.
Hives are caused by a Th2-type immune response that leads to the production of IgE antibodies, which in turn cause mast cells to release histamine.
Recently, we had a woman get relief from her hives within a half an hour after using this product! Obviously, its not going to work like this for everyone, but we have observed improvement in many who have tried it.
Given that approximately 70-80% of the immune tissue in the body is located in the gut, it is very clear that reducing gut permeability (i.e. a leaky gut that lets undigested particles by), can have a positive impact on an over-reactive immune system. One of the ways to help accomplish this improvement is with lactic acid-producing probiotics, or just the lactic acid itself, such as is in Molkosan. This product is a good example of where the science to explain exactly why or how something works just hasn't caught-up to the observed, and often unmistakable results!
So, how do you decide where to start? Some of these nutritional issues such as probiotics or Vitamin D are something that anyone can benefit from. But beyond that, where you start is on the issues that stand-out. If you suspect liver or bowel involvement, start there. If you respond well to botanicals, start with the one of the herbal formulas like Optimized Resveratrol, or if you have broad reactivity, try the Ecomer.
In conclusion, contrary to what some medical models would have us believe, we are not a bunch of segmented compartments. Rather, our systems are all connected, and one affects the others. This web-like interconnectivity is very apparent when it comes to the liver-gut-immune system.
Until next time,
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1408954/pdf/annsurg00930-0127.pdf the liver metabolises histamine
6. Alternative Medicine Review: Quercetin Monograph; Volume 16, Number 2, 1998. Thorne Research 2011. pp.172-194
8. Alternative Medicine Review: Oligomeric Proanthocyanidins (OPC's) Monograph; Volume 8, Number 4, 2003. Thorne Research. pp. 442-450
Disclaimer: The above information is provided for informational purposes only and is not intended to replace the advice of your physician.