Are allergy shots effective?

DEAR DOCTOR K:

I’m plagued by seasonal allergies. Should I consider immunotherapy?

DEAR READER:

Many people know all too well the misery of allergies — the sneezing, runny nose, postnasal drip, watery eyes and itchy throat. They try to fight back with allergy medications. But immunotherapy, also known as allergy shots, may be a better option.

I spoke to my colleague Dr. Paul Hesterberg, an instructor in medicine in the allergy and clinical immunology unit at Harvard-affiliated Massachusetts General Hospital. He noted that people often resist allergy shots because they fear injections and turn to them only as a last resort. But the shots can be an effective way to control symptoms that interfere with daily life. They can also help reduce dependence on allergy drugs.

Allergy shots will not eliminate your allergy. They change your immune response to better tolerate it. Medication treats symptoms; allergy shots help prevent the symptoms from occurring in the first place.

The shots are given with a small needle, just under the skin — not deep into the muscle. Sometimes there is temporary tenderness and redness at the spot where the shot has been given. On very rare occasions, there is a serious reaction called anaphylaxis that can cause a drop in blood pressure and breathing problems.

A recent study of adults aged 65 to 75 found allergy shots reduced symptoms by 55 percent after three years of therapy. The study also showed that the amount of medication this group needed to relieve symptoms dropped by 64 percent.

Shots are available for certain pollens, dust mites, mold, cat and dog hair and insect stings. There is no proof they work for food or drug allergies.

Shots are done in two phases: buildup and maintenance. The buildup phase involves receiving increasing amounts of the allergen — the substance that causes the allergic reaction — once or twice a week. This phase lasts three to six months.

The maintenance phase begins after reaching the full dosage. During this period, patients are injected on a monthly basis for up to three to five years.

As with any kind of treatment, allergy shots may not work for everyone, and they are not recommended for people with certain risk factors. These include some types of heart disease and severe, poorly controlled asthma.

If you are uneasy about injections, immunotherapy options that can be taken by mouth are available for certain allergies. They also are less likely to cause side effects than allergy shots and can be taken at home after your first dose in the doctor’s office. Oral immunotherapy is fairly new, and it is still not clear which therapy — injected or oral — is better.

The main question most of my patients ask when considering allergy immunotherapy is how much time it will take. As you can see from my description of what’s involved, it does involve many visits to the doctor’s office. Only you can trade off the amount of time it is going to take against the importance of reducing your allergy symptoms.