蕁麻疹的過敏性反應

若蕁麻疹屬於急性過敏反應時，患者在接觸致敏原後（如藥物、食物或昆蟲等）約一至兩小時內便會產生過敏反應。例如有些人士對蝦和蟹等海產類食物敏感，每當他們吃過此類食物時便會出現風疹。然而，若情況不太嚴重，患者不需服藥物便一天之內風疹會漸漸消失，直至再次接觸同樣食物時，風疹又會再次出現。

有時候，患者未必完全清楚自己對某種食物有過敏反應。有些人可能對食物添加劑或調味料如薑、蒜頭等過敏，而有些人甚至找不到致敏的源頭。食物過敏通常引發急性蕁麻疹，但只有5%的慢性蕁麻疹是由於食物過敏引致。

環境致敏原亦會造成急性蕁麻疹，如花粉症患者在春天的花粉季節時特別容易出現蕁麻疹；動物過敏者在接觸貓狗後都會長出蕁麻疹；而塵蟎過敏者或患有鼻敏感、哮喘人士，接觸了塵蟎或多塵的物件後，又或是久經未洗的毛衣時都會出蕁麻疹。

參考資料：<<了解過敏症>>

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，應向自己的過敏病科醫生查詢，而不應單倚賴以上提供的資料。

鼻敏感的不同狀況？

有調查發現，香港人大約有25%是鼻敏感患者。鼻敏感的主要原因是吸入致敏原令鼻腔出現發炎反應，徵狀跟一般的傷風感冒十分相似，即打噴嚏、流鼻水、鼻塞和鼻子癢等，並會持續一段時間。不少鼻敏感患者同樣地患有眼睛敏感問題（過敏性結膜炎），徵狀包括痕癢、出現紅筋、流眼水、眼腫等。

童時患有鼻敏感

大部份患有鼻敏感的病人都在兒童時期開始發病。在沒有適當的治療下，長時期鼻塞會令鼻竇和耳咽管無法暢通，因細菌感染而引起發炎，最終有機會出現併發症如中耳炎和鼻竇炎等。

慢性結膜炎

長期眼晴敏感可導致慢性結膜炎，徵狀包括上眼皮結膜出現腫粒、分泌呈繩狀、結膜水腫和怕光。嚴重時可導致白內障、角膜炎、角膜潰爛和變形，造成散光和其他視力問題。

兒童過度活躍症

有些關於兒童過度活躍症的研究發現，睡眠不足是成因之一。有超過40%的過度活躍症兒童有長期睡眠不足的問題，而鼻敏感是睡眠不足的一個重要原因。

參考資料: 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，應向自己的過敏病科醫生查詢，而不應單倚賴以上提供的資料。

Outgrowing Food Allergies

Reference information:  http://www.aaaai.org/ , www.allergy.hk


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. If a reaction occurs, have someone take you to the emergency room, even if symptoms subside. Afterwards, get follow-up care from an allergist.


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.

Symptoms of Allergic Reactions to Foods

Reference information: www.allergy.hk

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 999). 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.

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.

Tips to Remember: Food Allergy

Reference information: http://www.aaaai.org/

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.


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.

Pollen Allergy

Reference information: http://www.aaaai.org/,

Activities like camping can be fun, but they can also expose you to outdoor pollen as well as to stinging insects like bees, yellow jackets and wasps. If you have these allergies, avoid camping during high pollen seasons, take your medications with you and carry injectable epinephrine to treat reactions to stinging insects. If you have a severe insect-allergic reaction, get immediate emergency medical treatment. 

Walking, leisure biking and hiking are typically good activities for people with asthma or allergies. If you enjoy the mountains and have asthma, be careful if you are thinking of going above 5,000 feet, as oxygen levels decrease.

Cold weather sports such as cross-country skiing and ice hockey are more likely to make symptoms worse. Also, snorkeling is much safer than scuba diving.

An asthma treatment plan can help you keep your symptoms under control so that you can enjoy exercising or sports activities while traveling.

Bon voyage and safe travels!

Healthy Tips

• If your allergies or asthma are causing problems, have a pre-trip physical.

• Pack all medications, a peak flow meter and a copy of your physician's phone number.

• Consider buying travel medical insurance.

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. 

Enjoy Your Stay with Allergies and Asthma

Reference information: http://www.aaaai.org/,

Hotel rooms often have a lot of dust mites and molds in carpeting, mattresses and upholstered furniture. Fumes from cleaning products may also cause problems. Ask for a "green" room if available. If you are allergic to dust mites, you may want to bring your own dust-proof, zippered covers.

If you are sensitive to molds, request a sunny, dry room away from areas near indoor pools. Also, if you have allergies to any animals, ask about the hotel's pet policy, and request a room that has been pet-free.

Visiting family and friends in their homes can be risky if you have allergies or asthma. For instance, during the holidays, dust mites on ornaments and decorations, molds on Christmas trees, wet leaves and logs for wood-burning stoves and perfumes from scented candles can all trigger allergy or asthma symptoms.

If you have pet allergies, your trip may be more enjoyable if you avoid staying in the homes of family or friends with pets.

People with food allergies should be careful about eating home-cooked foods that may contain hidden food allergens.



Reference information:  www.allergy.hk , www.aaaai.org

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.

House dust mite

Reference information: http://www.polleninfo.org

Pollen which appear at unusual times of the annual cycle:

Usually the pollen season starts in spring and ends in late summer / autumn. Some plants however, flower late in the year and release nonetheless considerable amounts of pollen.

Cedars flower in late September / early October and may cause conspicuous yellowish precipitations similar to what we know from pine and spruce in certain years during May.

Ivy pollen becomes airborne in small amounts at about the same time.

different species of the cypress family may flower throughout the year and release some pollen. In the Mediterranean, cypress is sometimes already in December in full flower.

In late autumn one can notice in some years a yellowish dust layer here and there, composed of rust summer spores of Puccinia (black rust or stem rust on wheat).

long - distance pollen transport

During winter time, sand from the Sahara desert is transported by strong winds far north to Europe. We sometimes detect at such occasions very characteristic pollen grains from Ephedra, which flowers in late winter in the Atlas mountains.

In particular in Scandinavia, birch pollen allergic patients must often face surprising hayfever attacks in early spring although no birch is yet flowering far and wide. Long distance transport can deposit lots of birch pollen of southern origin by suitable weather conditions. Ambitious forcast models are under development, combining methods of meteorology, aerobiology and remot satellite sensing.

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. 

不同的脫敏治療

塵蟎

因氣候潮濕的關係，香港的塵蟎致敏原較多。接受塵蟎脫敏治療一般所需時間較長，以6個月至一年不等才有明顯效果。不少臨床測驗指出，脫敏治療能有效地減少鼻敏感、眼睛敏感及哮喘等問題。

濕疹

至於濕疹，需視乎患者本身的病情，除了因為過敏而引致濕疹病發外，亦有其他因素如細菌感染和皮膚受到環境因素刺激等，即使解決了環境過敏亦未必完全把濕疹根治。所以，濕疹患者在決定接受脫敏治療前必須了解清楚，其濕疹跟過敏是否有很大的直接關係。

鼻敏感

鼻敏感患者在進行脫敏治療的首六個月需要持續用藥，當鼻敏感病徵開始穩定時，約在脫敏治療的6個月後便可開始減少用藥，大部份患者接受脫敏治療約一年便不需要用藥了。

哮喘

大部份哮喘患者在進行脫敏治療後便可以減少所需要的吸入性類固醇。在治療初期因要控制患者的哮喘情況才可進行治療，所以並不建議患者在這階段停用吸入性類固醇。進入維持階段後便可視乎病情逐漸減少哮喘藥物。

參考資料: <<了解過敏症>>

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，應向自己的過敏病科醫生查詢，而不應單倚賴以上提供的資料。

Tips of Traveling with Allergies and Asthma

Reference information:www.allergy.hk , www.hkallergy.org

By car
Common allergens such as mites and molds lurk in carpeting, upholstery and ventilation systems. If you have pollen or mold allergies, and are traveling by car, close your windows and turn on the air conditioning to "do not re-circulate" mode.

Outdoor air pollution can make your symptoms worse. If traveling by car, think about driving during early morning or late evening when the air quality is often better and you can avoid heavy traffic. Don't travel in a car with someone who is smoking. If you use a nebulizer for your asthma, get a portable nebulizer.

By plane
If you have food or pet allergies, you may benefit by checking airline policies before traveling. Some have "nut free" flights. Some allow pets to travel as passengers, others do not. Make sure to carry two doses of portable, injectable epinephrine, in case you have a severe allergic reaction while in flight.

If you have severe asthma or other respiratory illnesses, your physician may tell you to take supplemental oxygen. No one can be refused travel for needing supplemental oxygen; however, this has to be arranged in advance.

If you have sinusitis or an ear infection, the changes in air pressure in the plane could cause significant pain. If possible, try to delay your travel until your symptoms improve.

The air in planes is very dry. You will feel much more comfortable if you use saline nasal spray once every hour to keep the membranes in your nose moist.


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.

免疫系統的主要功能是辨別有害和無害的物質

在日常生活中，過敏症其實已經周旋於你與我之間。在氣溫和季節性的氣候轉變時，你會有流鼻水、痕癢、打噴嚏，又或是吃完某種食物後，皮膚出現紅腫和痕癢，便證明了你可能患上過敏症。

過敏症是最常見的長期病患，當中包括鼻敏感、皮膚濕疹、哮喘、食物敏感、昆蟲敏感等等，一些平日時常接觸的東西，亦有可能會令你患上過敏症。

免疫反應

過敏症發生的原因是因為身體對本來無害的物質產生不正常的免疫反應。

免疫系統的主要功能是辨別有害和無害的物質，並對所有身體以外的物質作出反應。當有害物質如細菌和病毒入侵及破壞身體的組織時，身體便會發出危險訊息，使免疫系統即時辨認及記錄此物質，並於再次接觸時產生免疫反應。

另一方面，在接觸非病毒或細菌性的物質如花粉、塵蟎和食物時，由於它們沒有破壞身體組織，免疫系統在沒有危險訊息的情況便產生忍耐反應（即不會造成任何症狀），即使再次接觸時亦是沒有異樣。

因免疫系統誤認無害物質為有害，如某類食物、塵蟎，花粉等而產生活躍性的免疫反應時，便是過敏性反應。

參考資料：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，應向自己的過敏病科醫生查詢，而不應單倚賴以上提供的資料。