Is it best to take a country's local brand allergy medicine for allergies that only happen locally or is everything the same?
I'm not a doctor
But, most allergy pills are going to address the response that your body has to the allergen vs treat the specific allergen. Your response is always similar, right? Sneezing, itchy, watery eyes, congestion, headache..
The pills are just keeping your body from having such a big reaction.
Because of this, it seems like perhaps there are some pills that deal better with certain symptoms for you; you might need a different one if the symptoms are slightly different. I find some allergy pills don't work at all for my mixed seasonal and indoor allergies, but Cetirizine (Zyrtec generic) works great; that might not be the same for you.
What I'm getting at is I don't think taking a locally available drug, especially in a developed nation where the solutions are often the same as in the US, is going to fix the problem, but having a backup pill that works for the other set of reactions you have might help.
And be grateful, because a lot of doctors and researchers theorize that having an allergy response is actually your immune system doing a really great job of fighting. Hopefully you don't get sick much beyond that.
Is it safe to combine 2 or more medicines for seasonal allergies?
The drugs you have listed are all antihistamines. If someone combines two of them, it would have the same effect as doubling the dose of one of them. Since in general, we see more side effects with higher doses, that's what we can expect to happen. For example - diphenhydramine causes drowsiness, so combining it with another antihistamine will probably cause even more drowsiness. However, antihistamines are quite safe, which is why they are allowed to be sold over-the-counter.
For people with severe seasonal allergies, it is common to recommend the combination of 2 different classes of medications, usually a nasal steroid and an antihistamine.
What medicine is good for allergies?
Allegra (fexofenadine) works best for me. Claritin is joke, but has great marketing. I use mucinex occasionally when things get really runny, but generally try to avoid it. For asthma, Asthmanex has been worked well. My favorite prescription nasal medication is Omnaris. They will try to disuade you from it because of its cost, but it works well, so insist on at least trying it. Pataday antihistimine eye drops can be soothing if the allergen is bothering your eyes. I get allergy shots too. These are a God-send and definitely help greatly with Asthma due to allergic reactions as well as stuffiness and just the uncomfortable and gross runniness. Allergy shots will also lower your need for medications. And don't forget Benadryl! Awesome, but drying and will make you sleepy. Check the label. Dyphenhydramine (Benadryl) is *the* ingredient in many over-the-counter sleep medications ... just colored in a soothing blue, with twice the dose of regular benadryl (colored in hot hot pink). It is likely cheaper to buy Benadryl instead of sleep medication and take a double dose. But it does dry you out which can promote tooth decay if your mouth is dry and you sleep with your mouth open because breathing through your nose is not really working.