Allergic rhinitis and post-nasal drip can be treated, but patients should know the best way to do it, a doctor said Thursday.

Antihistamines are used to treat both conditions, but picking the right one is important, said Taing Tek Hong, as a guest on “Hello VOA.”

Sedating antihistamines, such as Benadryl and Clemastine, can work, he said. But these should be avoided in patients who need to drive or use dangerous equipment. Alternatives include non-sedating medicines like Zyrtec or Claritin. Most of these are found over the counter.

Decongestant sprays quickly reduce swelling of nasal tissues by shrinking the blood vessels, the doctor said. They improve breathing and drainage over the short term. The most common decongestant is Sudafed, an oral decongestant that temporarily reduce swelling of sinus and nasal tissues.

Montelukast, or Singulair, can be used by patients who do not wish to use nasal sprays or who have co-existing asthma, Taing Tek Hong said.

Nasonex is the only prescription nasal spray clinically proven to help prevent most seasonal nasal allergy symptoms in adults and children, he said.

It helps treat nasal allergy symptoms caused by dust mites, pet dander and tree and grass pollen.

Other treatments include immunotherapy, such as a weekly injection of a solution containing allergens that increases gradually, reducing the sensitivity to the allergen.

Surgery can help in complicated conditions, such as chronic sinusitis, severe septal deviation causing an obstruction, nasal polyps or other anatomical abnormalities, Taing Tek Hong said.

A caller from Kampong Cham province asked how a food allergy might be treated.

While many people assume they have an allergy after they experience a reaction to food, the doctor said, such allergies are rare. However, food intolerance can affect nearly everyone at some time, he said.