I think Claritin is very weak and mostly useless.

I use Zyrtec at night and sometimes rotate with Benadryl if it stops working.

I use them for my allergies. Spring and fall mostly but sometimes to help sleep too.

When I need it, I use Tagamet OTC 1 or 2 of those. But one has to be careful with Tagamet if using RX drugs. Many drugs interact with it. I don't use much and my blood pressure drug is not metabolized by the liver so that is okay for me. But I think Tagamet is the most efficient. If I have to I use it only at night.

One of my water fitration Brita pitchers developed algae in it!
That has never happened before. Just before I could see it, I started getting heart burn like I do upNorth! I had to take Tagamet for a WEEK... once we realized what was happening, I nuked the pitcher with bleach and the heartburn is now gone!

When people have severe allergies to food and/or drugs
an H2 blocker is often given with the antihistamine. This happens too with premedication for IV dyes and CAT scans etc.
Has to be Tagamet or Zantac, or Pepcid or Axid.
Proton pump drugs like Prilosec don't work on Histamine receptors.

The potency of antihistamines for allergy go:

Atarax>Benadryl>Zyrtec>chlopheniramine>Allegra>Cla ritin

Claritin requires activation by the liver to active metabolites, and that can take 3 hrs or more. And it can also raise liver enzymes in some people.

I think if you only use the H2 antagonists very occasionally, not much effect on nutrient absorption will occur. It is daily use for long periods that begin to affecting B12 and other things seriously.