SCRATCH TEST/PRICKTEST
Purpose:
A prick test is often used by allergists when a patient has clear allergy symptoms but is not certain which food is causing those symptoms (or whether the symptoms are caused by a food at all). They are often used when patients have hives, eczema, or hay fever symptoms.
Time:
20 to 30 minutes.
Advantages:
Prick tests are among the quickest allergy tests available. They are reasonably inexpensive, allow allergists to test a number of potential allergens at one time, and are usually not painful.
Disadvantages:
Prick tests are considered less sensitive than some other allergy tests, and a negative prick test may be followed up with other, more sensitive tests if a practitioner strongly suspects an allergy. Prick tests are generally not used when a reaction is considered life-threatening.
“False positives,” where a food someone tolerates well returns a positive test result, do sometimes occur. An allergist will make a final diagnosis of an allergy based not just on the prick test, but also on the patients symptoms and history.
How it works:
Prick tests (sometimes called scratch tests) are performed on the skin of the forearm or the back. Allergists put a small amount of an extract of a potential allergen into a shallow scratch. Within twenty to thirty minutes, a positive result will show as a hive, or wheal, on the scratch. The size of the hive may correlate with the intensity of the allergic reaction.
In the event of a severe reaction, the allergist will administer a rescue medication such as epinephrine or an antihistamine. Severe reactions to a prick test, however, are uncommon. (This is why they are generally not used to confirm life-threatening reactions — blood tests are much safer for that purpose.)
General Information about Allergy Injections
The following information is for patients who may be considering immunotherapy (allergy shots or injections) as part of their allergy treatment plan.
The goal of immunotherapy is to reduce allergic sensitivities. Treatment involves a series of injections given on a regular weekly or bi-weekly basis (preferred). The kinds of allergy injections prescribed, as well as the number and frequency of the injections, will be described in a discussion with Dr. Herrera and/or the nurse. The prescription is based on your particular symptoms, your examination and your skin test results.
Allergy injections are started at a low dosage.
The strength and amount of the injections are gradually increased over a period of months, until you reach the highest dosage that has been prescribed or a level above which there is a reaction. You’ll then continue “maintenance” injections at this level. The best maintenance dosage for an individual is one that achieves relief of symptoms without unpleasant side effects.
Improvement of allergy symptoms will be gradual. About 85% to 90% of patients given allergy injections receive significant reduction in their allergic symptoms. However, improvements usually occur over a period of three to six months.
The maximum benefit may not be reached until 12 to 24 months into treatment.
The duration of immunotherapy treatment varies greatly. The minimum treatment period for most patients is three to five years, and only in rare occasions is longer therapy necessary. In general, the injections should be continued until about one year beyond the time when allergic symptoms have come under control. Thus, the total duration of treatment has to be individualized. The duration depends on the nature of the allergic problem, the rate and completeness of recovery, and whether symptoms return when immunotherapy is discontinued.
Because allergy injections are extracts of substances to which you are allergic, you and the health care provider administering the injections will need to be alert to any signs that you are having an allergic reaction to the injection. Early indications of a reaction are described on the FAQ page and will be discussed during the office visit before you consent to immunotherapy. If you begin to develop local swelling (greater than two inches) at the injection site or have any other symptoms thatyou feel are due to the injection, please contact us before your next injection so that we may adjust the dosage.
Allergy injections should be given under the direct supervision of a physician, so that the physician can monitor potential problems and treat any reactions. If your injections are to be given somewhere other than in our office or clinic, we must have the name, address and telephone number of the physician who will assume the responsibility for administering your injections. We will provide you with a form to complete that will allow us to forward your extracts to another physician or medical facility. Allergenic extracts will be released only to a licensed physician.
After completing the initial series of injections, immunotherapy patients should have a follow-up visit. At that time, if your allergic symptoms are not clearly improving, the allergist-immunologist may make changes in your prescription to make it more effective for you. It is important for patients who are experiencing persistent allergic problems to have regular re-evaluations, usually at six- to 12-month intervals. Patients who are doing well, who are having no problems with their injections, and who have not developed any new medical problems should plan on a review of their treatment program with the doctor once a year.
