This can be an unpleasant symptom but fortunately, there are a few things your wife can do to ease the problem.
First of all, this issue is often linked to congestion. In someone with allergic rhinitis, inflammation in the nasal passages (and elsewhere) is triggered by contact with an allergen. This reduces the sense of smell and, since we also need smell to determine taste, this can be reduced too.
I go into these issues in a little more depth in my blog 'Allergic rhinitis and loss of taste and smell'.
In terms of reducing the problem, it is best to first look at congestion. This may be eased with Sinuforce Nasal Spray which reduces swelling in the mucous membranes whilst leaving their natural protective function intact.
Additionally, inhaling steam can be a great tactic in reducing congestion. I think having a hot shower or bath or taking a hot drink, are some of the safest and most pleasant ways to do this. You could try opting for the likes of nettle tea which is a natural anti-histamine.
Other than this, I would offer some general advice about dealing with allergic rhinitis:
Do you have questions? Please feel free to ask.
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