過敏測試有什麼種類?

為了有效地治療過敏病，準確的診斷是必要的。病人詳細的病歷與體格檢查，再配合測試，便能讓醫生更清楚了解過敏病原，同時亦可使我們能按照您的情況提供合適的治療方案。

皮膚點刺測試：

以診斷動物的毛皮垢屑, 塵蟎, 黴菌, 花粉, 黃蜂、蜜蜂等蜇棘昆蟲的毒液, 食物, 橡膠, 藥物，如盤尼西林、局部麻醉藥… 

過敏血液測試

激發式測試以診斷阿斯匹靈藥物敏感, 食物和食品添加劑過敏, 過敏哮喘

盤尼西林及其它藥物過敏, 特殊過敏原反應,

晚發性過敏反應皮膚測試：細胞免疫功能測試, 結核病測試

肺部功能測試：

哮喘診斷, 確定哮喘治療的成效

鼻黏膜診斷過敏, 傳染

斑貼測試診斷：接觸性皮膚炎, 與食物過敏相關的異位性皮膚炎(濕疹)

參考資料: http://www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

過敏症

過敏症在現今的社會裡十分普遍，患者有不斷上升的趨勢。不少患者和父母都問及有什麼方法可以防止小朋友將來患上過敏症？想知如何防止過敏症，首先要明白過敏症的自然歷史和高危因素。

過敏症的歷史

大多數過敏症患者會在嬰兒時期開始，而濕疹是嬰兒早期及常見的過敏症症狀；還有，嬰兒亦有可能患上腸胃過敏、喘鳴（不算是哮喘，但經常會有氣喘的問題），在這段時間，牛奶是最常見的食物致敏原。

食物過敏多發病在三歲或以下的小童，但當他們長大後便會轉移對環境致敏原產生敏感；當中包括室內致敏原，如塵蟎和動物，及室外致敏原，如花粉和霉菌。此時，鼻敏感和哮喘等問題亦開始出現。

有研究發現，若已患有一種過敏症的小童，他日後患上其他過敏的機會更高。特別是異位性皮炎患者，他們極有可能患上哮喘及食物過敏；對食物過敏的小童患上哮喘的機會比正常人高，而患鼻敏感的小童亦是哮喘的高危人士。

參考資料: http://www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

脫敏治療

過敏疾病鼻敏感，過敏性結膜炎(眼睛過敏)和哮喘都是慢性疾病。 這些疾病是由免疫系统對無害的物質如花粉、塵蟎、黴菌孢子和動物的毛皮垢屑等產生的不正常反應。 現時的藥物如類固醇和抗組胺能有效地控制敏感症狀，然而根治的選擇是脫敏治療。

所用的過敏原疫苗是根據病人的敏感測試結果而配製。定期注射過敏原疫苗會導致一種稱為免疫忍耐的反應。此反應是因產生阻攔抗體和抑壓性 T 細胞而出現。當患者對過敏原的敏感反應日益減少時，症狀也得到舒緩。研究表示，經過三至五年的治療後，即使治療中斷後效果亦會長期持續。

在小兒階段出現的鼻炎是導致哮喘的重要因素之一。研究¹顯示，因鼻炎而接受過敏原免疫療法的小孩可將患哮喘的風險減少達2.5倍，而此情況在治療後可持續十年以上。

如果環境過敏是導致皮膚炎病人發病的主要因素，脫敏治療可有效地減低患者發病的嚴重性。傳統脫敏治療是利用皮下注射治療，新一代的脫敏治療方法如舌下脫敏治療已發展到更方便的層面，適合某類病人使用。

參考資料: http://www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

藥物過敏治療 Allergen Immunotherapy in Hong Kong

Allergic diseases such as allergic rhinitis (nasal allergy), allergic conjunctivitis (ocular allergy) and asthma are chronic diseases.  These diseases are caused by the immune system reacting inappropriately to normally harmless substances such as pollens, dust mites, mold spores and animal dander.  While there are drugs such as steroids and antihistamines that can effectively control the symptoms, the only option for eliminating the root cause of the problem remains allergen immunotherapy (also called desensitization, hyposensitization or allergy shots).

Allergen extracts are prepared according to the sensitivities of the individual.  The extracts are administered at regular intervals to induce a response called immune tolerance.  The tolerance response is achieved by the production of blocking antibodies and regulatory T cells.  When this happens, the patient’s sensitivity to the allergens progressively diminishes, and symptoms also decline.  Studies have shown that after three to five years of treatment, the effectiveness persists long-term even after treatment is discontinued.

Allergic rhinitis in childhood is a risk factor for the development of asthma.  A study shows that children who received allergen immunotherapy for allergic rhinitis have 2.5-fold reduced risk of developing asthma.  This effect is still evident 10 years after treatment.

Recent studies have also shown that for a subset of patients with atopic dermatitis, where environmental allergy is a major factor in their illness, immunotherapy is effective in reducing the severity of their skin disease.

Allergen immunotherapy has traditionally been administered by subcutaneous injections. Newer forms of treatment such as sublingual immunotherapy have been developed that are more convenient, and maybe suitable for selected patients

Reference information: http://www.allergy.hk

The information aims to provide educational purpose only. Anyone reading it should consult physician before considering treatment and should not rely on the information above.

藥物過敏治療

藥物過敏屬遺傳性問題。據統計顯示，患有一種藥物過敏者對其他藥物出現過敏的機會較正常人士約高出30%－40%；如患者對兩種不同藥物有過敏反應，他會就其他藥物的過敏機會則比正常人高出十倍。所以，有藥物過敏病歷的人士必須謹守使用藥物，有需要時才服用抗生素，如一般的傷風感冒和其他非細菌感染時便不要亂用抗生素藥物了。

自我監測

當病人服食藥物後懷疑對該藥過敏時，應立即查詢醫生及商討是否停止服用，以及轉用其他相同功能的藥物。

醫生的角色

醫生也要確診患者是否因過敏藥物功能反應，還是免疫系統所致；若是免疫性反應的過敏時，可轉用結構不同但功能相約的藥物；反之，因藥物功能造成的過敏反應如阿斯匹靈，替代藥物在結構上完全不相關，但功能是相同的話，亦會引起過敏問題。醫生須了解清楚才可決定使用哪種替代藥物。

然而，患者或許會在同一時間服食多種藥物而產生過敏，此情況下較難判斷過敏的元兇。基於某些藥物引起過敏反應的機會較大，醫生需評估病人的過敏反應，才可確定導致過敏的藥物。

最後，不少有過敏反應的病人在停藥後都會自行痊癒，亦有些病人需要利用藥物醫治。當患者痊癒後，倘若需要再次服食此類藥物時，最好先進行測試。

激發性測試

在醫生的監控下，讓患者服食小劑量藥物作測試。當病人出現過敏反應時便立刻停止，並進行藥物治療。可能有非常嚴重過敏反應的患着，不適宜進行激發性測試。

參考資料: http://www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

藥物過敏-抗生素 / 脫敏治療

抗生素

常見引致過敏的藥物盤尼西林（Penicillins），發病率佔所有抗生素的50%，病徵主要是皮疹和血管性水腫（Angioedema）。

盤尼西林類藥物阿莫西林（Amoxycillin）和氨比西林（Ampicillin）構成所有藥物過敏症個案之15%－20%。然而，病人在服食盤尼西林後長出皮疹，便誤以為是對此藥有過敏反應，但其實皮疹可能是感染引起，跟藥物敏感並無關係。若患者想確定是否對盤尼西林過敏時，可進行皮膚測試。一般而言，大部份的盤尼西林抗體並不是針對它本身，而是經身體分解後的副產品，所以需利用副產品進行皮膚測試。如測試結果呈陰性反應，然後再試食，肯定沒有過敏症狀後，便可排除對盤尼西林有急性過敏的可能性。倘若患者對盤尼西林有急性過敏反應，但感染不能使用其他抗生素醫治，此時可考慮盤尼西林脫敏治療（Penicillin Desensitization）。

有數據顯示，懐疑自己對盤尼西林過敏的成年人只有15%是真正的患者，而小童則只有40%。

什麼是脫敏治療？

治療時首先服用非常低劑量的盤尼西林，然後慢慢增加到所需要的劑量。完成脫敏治療後，患者便可繼續服用盤尼西林。不過要注意一點；這個脫敏並非永久有效，若患者脫敏後不持續服食盤尼西林時，過敏反應則會復發。及後患者需要再次服用盤尼西林的話，便需要再進行脫敏治療。

參考資料: http://www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

藥物過敏 (Drug Allergy)

身體免疫系統對藥物作出的不良反應，不同藥物會引起不同的免疫性反應。整體而言，藥物過敏是一項非常複雜的議題。

因藥物引起的不良反應，多數是藥物的功能性反應，如抗生素去除腸內細菌，令不少病人在服藥後有腹瀉現象，而某種血壓藥則會令病人的心跳加速等；此外，其他較為罕見的不良反應，如有少部份含毒性的藥物會影響肝臟或骨髓功能，以上種種全屬於藥物直接引起的不良反應，而非藥物過敏。

當免疫系統對藥物產生不正常的反應時，便會出現藥物過敏的現象；換句話說，真正的藥物過敏其實屬於免疫反應。

免疫反應的兩大分類

早發性反應

藥物與免疫球蛋白E（IgE）結合後導致肥大細胞釋放因子。患者在服藥或注射後可在數分鐘內產生嚴重的過敏反應，如長出風疹、水腫、血壓驟降、氣管收窄導致死亡等，情況跟食物過敏相似。

遲發性反應

通常在三至七日後發生，患者皮膚出免疫, 藥物過敏，昆蟲過敏, 風疹現紅疹、痕癢、皮下出血等。亦會有高危險性的皮膚反應，導致皮膚壞死及嚴重剝落，可以構成性命危險。

藥物過敏引起的反應和病徵

皮膚最常受藥物過敏影響。當患者食同一種藥物，都會在同一位置出疹。最初為紅疹，顏色慢慢變深，皮膚可能會潰爛。患者一般在停止服用藥物便會痊癒。

除了皮膚，藥物過敏亦影響身體的其他器官，如嗜酸性粒細胞（Eosinophils）影響肝和腎，導致病人出現急性肝衰竭（Acute Liver Failure）和腎衰竭（Kidney Failure），它亦會影響肺和心臟，令病人有急性心衰竭（Acute Heart Failure）、心肌發炎（Mycarditis）和慢性心衰竭（Chronic Heart Failure）等。

此外，另一常見的藥物過敏反應是血清症（Serum Sickness）；病人在服用藥物後，免疫抗體跟藥物結合後會積聚在微絲血管內造成發炎，引致皮疹性血管炎（Cutaneous Vasculitis）、腎小球發炎（Glomerulonephritis）、關節發炎，或是腸胃的血管發炎而產生的腹痛、腹瀉等。

參考資料: http://www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

Cough in Children – quick tips for parent

As a parent, hearing your child cough may make you feel uneasy, yet an occasional cough doesn't always mean there is a problem. Cough protects your child's body by removing mucus, irritating substances and infections from his or her respiratory tract.
Children can cough several times a day and have coughing episodes lasting up to a couple of weeks if they have viral infections. However, coughing that lasts more than two to three weeks should prompt a visit to your physician.

Acute Cough in Children (Two Weeks or Less)
The majority of children have brief repeated periods of coughing due to viral upper respiratory tract infections, such as the common cold. Healthy preschool children in day care can have up to eight viral respiratory infections with a cough every year, each lasting about 10 days.
Infrequently, a cough occurs because of a foreign body in the airway. This may occur after an episode of choking, but sometimes the choking episode might not be noticed, especially in younger children. See your physician quickly if you think this is possible.

Causes of Chronic Cough
There are many different causes for a persistent or chronic cough in children.

·         Asthma
Most children with asthma have inflamed or swollen airways, which commonly cause wheezing. But sometimes the only symptom is a cough that is made worse by viral infections, that happens while your child is asleep, or may be triggered by exercise and cold air.

·         Nasal and Sinus Disease
Postnasal drip caused by rhinitis or a sinus infection (sinusitis) can produce chronic cough. Usually other symptoms are present, but sometimes the only symptom you notice is the cough.

Allergic rhinitis may be seasonal or year-round. The seasonal allergy, often called "hay fever," typically occurs in the spring, summer or fall. Symptoms include sneezing, stuffy or runny nose and itching in the nose, eyes or on the roof of the mouth. When the symptoms are year-round, they may be caused by exposure to indoor allergens such as dust mites, indoor molds or pets. An allergist can perform testing to find out to what your child is allergic.

·         Stomach and Esophageal Causes of Cough
In some children, the cause of chronic cough is stomach fluid moving back up the throat. This is called "reflux" and may occur silently without heartburn. Some children may develop a hoarse voice and/or choking as symptoms. To determine if this is the cause, your physician may perform tests to see if acid is refluxing up out of the stomach.

·         Post-Viral Cough
After having a viral respiratory infection, otherwise healthy children can have a cough lasting for weeks. There is no specific therapy for this cough, which eventually goes away. Cough suppressant medications can be tried in school-age children, but they don't always solve the problem.

·         Bacterial Infection of the Lower Airway
Bacteria sometimes can infect the lower airways and cause irritation and cough. It's unknown why this happens, and sometimes the best course of action isn't clear. Your physician will help you sort out whether this may be relevant in your child.

·         Inhaled Foreign Body
Foreign bodies, such as toys and food, can be accidentally inhaled at any age, but most commonly occurs at ages two to four years. It can cause a cough to persist for many weeks to months until it is discovered.

·         "Habit" Cough
This is a persistent cough that has no clear physical cause. It occasionally persists after a simple viral respiratory infection. The cough is typically dry and repetitive or is a "honking" cough. Habit cough usually occurs only when your child is awake, not sleeping. A neuromuscular tic can also cause this kind of cough.

·         Irritant Cough
Exposure to tobacco smoke and other pollutants (smoke and exhaust from wood burning, air pollution and exhaust from vehicles) can lead to cough and may worsen the cough associated with asthma or rhinitis.

Treatment
If your child has a daytime cough after a viral respiratory infection, it usually doesn't need any specific treatment-particularly if it goes away in one or two weeks.
The main treatment for chronic cough should be based on the underlying cause. This search for the cause usually involves visiting your physician. Also visit your physician if your child's cough is increasingly frustrating, persists longer than you think is reasonable, if blood is coughed up or if the cough interferes with your child's daily activities.
Over-the-counter mucous thinning agents such as guaifenesin, and cough suppressing medications such as dextromethorphan can be tried. Although most of the over-the-counter cough medications are not thought to be particularly effective, it is possible that one might work better in your child than in other children.
If you think your child may have asthma, make an appointment with an allergist/immunologist, often referred to as an allergist. An allergist is the best physician to diagnose and treat this disease.

Healthy Tips

• A cough protects your child's body by removing mucus, irritating substances and infections from his or her respiratory tract.
• If your child has a cough that lasts more than two to three weeks, schedule a visit with your physician.
• Coughing that lasts more than two weeks is considered chronic. It may be caused by asthma, allergic rhinitis (hay fever), reflux or other causes. An allergist is often the best specialist to determine the cause.

Reference source: http://www.aaaai.org/patients/publicedmat/tips/coughinchildren.stm

The above information serve as an education purpose only, you are encourage to consult with your allergist for appropriate diagnosis and treatment.

食物過敏 -診斷及治療 (food allergy)

診斷食物過敏

首先，醫生會詳細詢問病人的病歷，特別是病人及其家族的過敏史如病徵、發病時間、發病頻率及食物種類等，而病人亦最好準備他的病症日誌，記下自己進食食物的種類和發病情況， 以便確診。

測試食物過敏

就急性過敏反應，除了進行準確度和靈敏度較高的皮膚點刺測試（Skin Prick Test）外，也可利用過敏血液測試（Blood Test for Allergy），辨認病人的血清是否含有對過敏原的IgE抗體。

然而，不少食物致敏原會在消化過程中被損壞，加上腸胃本身亦可避免吸入致敏原，因此食物經消化後不一定會造成過敏反應。在此情況下，醫生會建議病人進行食物激發測試（Challenge Test），病人先禁食懷疑致敏的食物一段時間（約一至兩星期），然後在醫生的觀察下試食此食物，以作診斷。

食物激發測試方式

開放式	簡單地給病人作漸進式的進食
單盲式	用安慰劑混淆病人，使其無法就作進食的食物作出估計，排除病人的心理障礙。
雙盲安慰劑受控	用安慰劑混淆病人， 排除病人的心理障礙。 觀察者亦事先不知測試物的來源，排除觀察者的偏見。做研究時比較常用。

參考資料: http://www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

食物過敏 -食物間的交叉反應 (food allergy, hong kong)

食物致敏原

一般的食物致敏原是食物中的蛋白質，尤其是醣蛋白(Glycoprotein)，具有抗熱和抗酸性的功效，即使煮熟及消化後，它依然保持敏感原的特質。大部分兒童的食物過敏都是由雞蛋、牛奶、花生、黃豆和小麥引起，而花生、腰果、貝殼類、魚類則是成年人中常見的食物致敏原。

大部份食物敏感患者只對一類食物過敏，然而，食物間存在著交叉反應（Cross-Reactivity），即是患者對某種食物過敏之同時，其相關的食物家族亦會有過敏反應。

較常出現交叉反應的食物種類：

²  魚類                ：患者常對多種甚至所有魚類都有過敏反應；

²  貝殼類海鮮    ：對貝殼類海鮮敏感患者，平均對三至四種不同的貝殼類海產亦有敏感。甚至有部份病人對所有甲殼類敏感如蝦、蟹、龍蝦等。蜆和蠔是貝殼類中較常有交叉反應，鮑魚類屬單殼海產，與螺類（田螺）有交叉反應。

其他的交叉反應：

²  堅果類（即合桃、果仁、腰果），約有40%的交叉反應。對腰果敏感患者幾乎是100%對開心果有敏感反應；

²  五穀類，約有４％的小麥敏感病人不能進食燕麥等穀類食物；

²  豆類約有5%的交叉反應。黃豆跟花生有交叉反應。

參考資料: http://www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

Hong Kong Allergy Tips: Food Allergy

Reference source:

http://www.aaaai.org/patients/publicedmat/tips/foodallergy.stm

If you have a Food Allergy, your immune system overreacts to a food. This is caused by an antibody called IgE (Immunoglobulin E), which is found in people with allergies. Food Allergy is more likely to develop in someone who has family members with allergies. Symptoms may occur after you consume even a tiny amount of the food.
Most allergens can cause reactions even after they are cooked or have undergone digestion in the intestines. There are some exceptions. For example, some allergens (usually fruits and vegetables) cause allergic reactions only if eaten in their raw form. Symptoms are usually limited to the mouth and throat.
The most common food allergens are the proteins in cow's milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts.

In some food groups, especially tree nuts and seafood, an allergy to one member of a food family may result in the person being allergic to other members of the same group. This is known as cross-reactivity.
Cross-reactivity is not as common with foods from animal groups. For example, people allergic to cow's milk can usually eat beef, and patients allergic to eggs can usually eat chicken.

With shellfish, crustaceans (shrimp, crab and lobster) are most likely to cause an allergic reaction. Molluscan shellfish (clams, oysters, scallops, mussels, abalone, etc.) can cause allergic reactions, but reactions to these shellfish are less common. Occasionally, people are allergic to both types of shellfish. 

Symptoms of Allergic Reactions to Foods
Symptoms of allergic reactions are generally seen on the skin (hives, itchiness, swelling of the skin). Gastrointestinal symptoms may include vomiting and diarrhea. Respiratory symptoms may accompany skin and gastrointestinal symptoms, but don't usually occur alone.

Severe Allergic Reactions
Anaphylaxis (pronounced an-a-fi-LAK-sis) is a serious allergic reaction that happens very quickly. Without immediate treatment-an injection of epinephrine (adrenalin) and expert care-anaphylaxis can be fatal. Follow-up care by an allergist/immunologist, often referred to as an allergist, is essential.
Symptoms of anaphylaxis may include difficulty breathing, dizziness or loss of consciousness. If you have any of these symptoms, particularly after eating, seek medical care immediately (call 911). Don't wait to see if your symptoms go away or get better on their own.

Diagnosis
An allergist is the best qualified professional to diagnose Food Allergy. Your allergist will take a thorough medical history, followed by a physical examination. You may be asked about contents of the foods, the frequency, seasonality, severity and nature of your symptoms and the amount of time between eating a food and any reaction.

Allergy skin tests may determine which foods, if any, trigger your allergic symptoms. In skin testing, a small amount of extract made from the food is placed on the back or arm. If a raised bump or small hive develops within 20 minutes, it indicates a possible allergy. If it does not develop, the test is negative. It is uncommon for someone with a negative skin test to have an IgE-mediated Food Allergy. 

In certain cases, such as in patients with severe eczema, an allergy skin test cannot be done. Your doctor may recommend a blood test. False positive results may occur with both skin and blood testing. Food challenges are often required to confirm the diagnosis. Food challenges are done by consuming the food in a medical setting to determine if that food causes a reaction.

Outgrowing Food Allergies
Most children outgrow cow's milk, egg, soy and wheat allergy, even if they have a history of a severe reaction. About 20% of children with peanut allergy will outgrow it. About 9% of children with tree nut allergy will outgrow it. Your allergist can help you learn when your child might outgrow a Food Allergy.

Treatment
The best way to treat Food Allergy is to avoid the foods that trigger your allergy. Although it has been shown that just smelling peanut butter will not cause a reaction, sometimes food allergens can be airborne, especially in steam, and can cause reactions. Boiling or simmering seafood is a particular offender.
Always ask about ingredients when eating at restaurants or when you are eating foods prepared by family or friends. 

Carefully read food labels. The United States and some other countries require that eight major food allergens are to be listed in common language, for example, "milk" rather than a scientific or technical term, like "casein."
Carry and know how to use injectable epinephrine and antihistamines to treat emergency reactions. Teach family members and other people close to you how to use epinephrine, and wear an ID bracelet that describes your allergy. If a reaction occurs, have someone take you to the emergency room, even if symptoms subside. Afterwards, get follow-up care from an allergist.

Food allergies can be confusing and isolating. For support, contact the Food Allergy & Anaphylaxis Network (FAAN) at (800) 929-4040 or visit www.foodallergy.org. 

Healthy Tips

• The most common food allergens are the proteins in cow's milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts.
• An allergist is the best qualified professional to diagnose a Food Allergy. Testing performed by an allergist often helps determine if foods are causing your symptoms.
• Some food allergies can be outgrown.
• The best treatment is to avoid the foods that cause your reaction.
• Read food labels carefully and ask about ingredients at restaurants or when eating food prepared by another person.

食物過敏與其他過敏問題(Hong Kong allergy review)

參考資料: http://www.allergy.hk

濕疹與食物過敏

據研究指出，約有40%的濕疹幼兒（即三歲以下的兒童）同時患有食物過敏問題，他們在再接觸過敏食物時便會令濕疹惡化。常見的食物致敏原有雞蛋、牛奶、黃豆、小麥及花生等。

【食物過敏引起的慢性反應便是濕疹的說法】並不正確。近年有不少研究顯示，濕疹才是引起食物過敏的原因。濕疹病人因皮膚缺乏屏障功能，使免疫系統經常受到外來致敏原的刺激，造成過敏反應。對於年幼的濕疹患者，可先診斷有否食物過敏問題，從而考慮戒掉致敏食物令濕疹病情得以改善。

還有其他跟食物過敏有關的疾病如偏頭痛、兒童注意力缺乏的過動症、類風濕關節炎及一些癲癇症等，但亦只是較罕見的問題。

其他過敏症與食物過敏

其他過敏症	同時患有食物過敏的百分比
濕疹病人	幼兒約 40% ， 成人約 5％
急性蕁麻疹病人	約20％
哮喘病人	5－6%
致命性過敏	40－60%

絕大部份的慢性蕁麻疹都並非食物過敏引起的。患有食物過敏的哮喘病人同時患有異位性皮膚炎十分普遍；換言之，沒有濕疹的哮喘病人極少與食物過敏有關。

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

食物過敏分類 (Hong Kong allergy review)

參考資料: http://www.allergy.hk

 

致命性食物過敏

大部份食物過敏而死亡的個案在生前是知道自己患有食物敏感，但延遲使用腎上腺素而導致死亡；換言之，因笫一次食物過敏而死亡的個案並不常見。對於患有嚴重哮喘及年青患有食物過敏的人士便要份外小心；有些病人會把食物過敏誤以為哮喘病發而延遲醫治。

急性過敏反應

因IgE免疫球蛋白E引起的急性過敏反應，病人會長出蕁麻疹，同時有可能有肚痛、肚瀉、嘔吐、喉嚨腫脹、氣管收窄和血壓驟降等症狀，然而，亦約有20－30%的病人沒有以上症狀，當他們出現食物過敏時會誤以為是哮喘發作，久藥無效而引致性命危險。

口腔過敏綜合症

同樣是由IgE免疫球蛋白E導致的過敏反應，患者同時對花粉敏感。因花粉和蔬果的致敏原產生交叉反應，所以患者在接觸新鮮蔬果後，口腔會出現痕癢現象。

嗜酸性細胞炎症

屬於慢性過敏反應，可影響腸胃系統如食道、胃部、小腸及大腸。患有嗜酸性細胞炎症者會有胃液倒流和肚痛等症狀，嬰兒會有可能出現嘔吐、腹瀉，甚至大便出血，情況嚴重時更會引致營養不良，影響嬰兒的正常發育。

腹腔疾病（Celiac Disease）

腹腔疾病可引發腸胃炎，嚴重損害小腸絨毛造成萎縮，導致腸胃吸收不良、腹痛、腹瀉等情況，若久病不醫更會增加腸胃淋巴癌的風險；除此之外，麩質或麵筋敏感亦會引發疱疹皮膚炎，並會在腹部和大腿上形成非常痕癢的水泡。東方人患此類疾病的個案極少。

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。

食物過敏 - 不正常的免疫反應

簡單來說，當食物進入身體後引起的不正常免疫反應，便是食物過敏。食物過敏可以分成由免疫球蛋白E (IgE)造成的早發性或急性過敏反應，以及因淋巴球細胞產生的晚發性或延遲過敏反應，兩者症狀各有不同。前者病人在發病時會有急性過敏反應、口腔過敏綜合症或蕁麻疹水腫等問題，而後者則會誘發嗜酸細胞性食道炎、胃炎、腸胃炎或濕疹。亦有罕見的非IgE食物敏感包括結腸炎、腹腔性疾病（Celiac Disease）或疱疹樣皮膚炎（Dermatitis Herpetiformis）等。

有些香港病人會把「食物過敏」與「食物不耐症」混淆。「食物不耐症」多數因消化不良或對某種食物／成份不吸收引起的，並非免疫系統反應，如病人或因腸胃系統缺乏酵素消化乳糖和其他蛋白質或脂肪。又或是食品中含有藥性物質、如胺基酸等，當患者接觸此類食物時便會導致腸胃或神經系統症狀。還有一些心理因素，如厭食症患者每每在進食時感到不適等；然而，單是食物不耐症導致有生命危險的情況十分少見。

參考資料: http://www.allergy.hk

以上所提供的資訊僅作為教育及參考用途，如果你有任何醫療問題，應向自己的醫生查詢，而不應單倚賴以上提供的資料。