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    Penicillin
    The penicillin family
    Penicillin belongs to a family of drugs called beta-lactam antibiotics. Included in this family are the commonly prescribed drugs ampicillin and amoxicillin. These medications are most often used to treat skin, ear, sinus and upper respiratory infections. They are relatively inexpensive and generally effective at eradicating many common bacterial infections. They aren't effective against viruses, however, so they aren't useful against the common cold.

    How penicillin allergy develops
    No one is born allergic to penicillin, but you can develop an allergy to the drug once you've been exposed to it. After that, re-exposure to penicillin or related antibiotics can trigger an allergic reaction.

    Allergic reactions occur because your immune system responds to the drug as if it were a harmful substance instead of a helpful remedy. For reasons not fully understood, your body creates antibodies called immunoglobulin to attack the medication. In most cases of penicillin allergy, the type of immunoglobulin that causes the most problems is type E (IgE). For the small percentage of people who develop IgE antibodies, symptoms range from annoying to life-threatening.


    An anaphylactic reaction
    The most severe type of reaction is what's called an anaphylactic  reaction, or anaphylaxis. The airway tubes (bronchi) leading into your lungs may constrict, making it hard to breathe. You might break out in hives, and your vocal cords, lips or tongue may swell. Your blood pressure may drop to life-threatening levels, making you feel dizzy or causing you to lose consciousness.

    Anaphylaxis
    An anaphylactic reaction usually occurs about 5 minutes to 2 hours after you take the penicillin. If you begin to have symptoms of a severe reaction after taking any medication, though, seek medical attention immediately.

    Drug allergies
    Most other allergic reactions to penicillin occur after 2 to 3 days and aren't as severe or life-threatening. Often, the allergy will show up as either hives or rashes, which can be itchy or irritating. These rashes may be confined to one part of your body, or they may spread to several areas. Sometimes the reaction causes various parts of your body to swell, such as your lips, face or hands. Delayed reactions sometimes occur several weeks later.

    Approaches to penicillin allergy
    If you develop an allergy to penicillin, this doesn't mean you're necessarily allergic to all antibiotics. Your doctor may be able to give you an antibiotic that is distantly related to penicillin without causing any problems. For example, among people with positive skin tests for penicillin allergy, only a small percentage are also allergic to a group of broad-spectrum antibiotics called cephalosporin's. However, this risk is great enough that people allergic to penicillin should be cautious about taking those drugs.

    If your doctor recommends that you avoid penicillin and cephalosporin's, you can still take antibiotics totally unrelated to penicillin to combat infections. However, these alternative medications may be more expensive and less effective than those related to penicillin.
    If a penicillin allergy is suspected and you need to take penicillin for an infection, the best way to confirm the presence or absence of penicillin allergy is with a skin test. This is done by injecting a tiny amount of the drug into your skin and watching that part of your body for signs of inflammation.

    Allergy tests
    If the skin test for penicillin allergy is positive, you're at an increased risk of a reaction if you take penicillin or closely related antibiotics. If you have a history of anaphylaxis within the first hour of taking penicillin and you also have a positive skin test, you have at least a 50 percent chance of having a reaction if you take penicillin again.

    Even if you've had an allergic reaction to penicillin in the past, it may be useful to have the test done again if you need to take penicillin for an infection. With time, many people lose their allergy to penicillin — if the suspected allergic response was actually due to penicillin.
    If you've ever had an allergy to penicillin, don't try the drug again on your own to see if your allergy has disappeared. This is very risky because a serious reaction could occur.

    It's also important to know what it means if you have a negative skin test for penicillin allergy. It doesn't mean that you're free of penicillin allergy. It means that your risk of penicillin allergy is roughly the same as that of the general population — about 2 percent. Furthermore, people can develop a new allergy to penicillin over time. Most of the time, your doctor will be able to prescribe penicillin or a related antibiotic if your skin test is negative.

    There are times when doctors try to weaken and eventually overcome a person's sensitivity to the penicillin allergen (desensitization). They do this by administering small but gradually increasing doses of penicillin orally or intravenously. Because desensitization can trigger a life-threatening reaction, however, it is only attempted in a controlled hospital setting — and only when penicillin is absolutely necessary.

    The bottom line
    The main strategy for penicillin allergy is avoiding the drug and its chemical relatives. Always report your allergies to penicillin, or any drug, every time you visit medical professionals. It also may be a good idea to wear a bracelet that describes your allergy or carry a medical alert card in your wallet or purse.
     

     
    Symptoms of Anaphylaxis
       
    • generalised flushing of the skin
    • nettle rash (hives) anywhere on the body
    • sense of impending doom
    • swelling of throat and mouth
    • difficulty in swallowing or speaking
    • alterations in heart rate
    • severe asthma
    • abdominal pain, nausea and vomiting
    • sudden feeling of weakness (drop in blood pressure)
    • collapse and unconsciousness

    Nobody would necessarily experience all of these symptoms.

    Some people find that the allergy symptoms they experience are always mild. For example, there may be a tingling or itching in the mouth, or a localised rash - nothing more. This is not serious in itself, and may be treated with oral antihistamines. However, in some cases symptoms may become worse over time. It is wise in all cases to make an appointment with the doctor and seek a referral to a specialist allergy clinic.

    If there is marked difficulty in breathing or swallowing, and/or a sudden weakness or floppiness, regard these as serious symptoms requiring immediate treatment.

    If you have suffered a bad allergic reaction in the past - whatever the cause - then any future reaction may also be severe. See your GP and request a referral to an NHS allergy clinic. If you have asthma as well as allergies a referral is particularly important. Where foods such as nuts, seeds, shellfish and fish are concerned, even mild symptoms should not be ignored because future reactions may be severe. This also applies to drugs, insect stings or latex. Ask your GP to refer you. Any GP seeking to locate a reputable NHS allergy clinic can refer to the handbook issued by the British Society for Allergy and Clinical Immunology (020 8398 9240).


     
    Risk Indicator

    If you suspect you are having, or might have an anaphylactic attack, SEEK MEDICAL ASSISTANCE IMMEDIATELY. If you suffer an attack, and have no medication such as Epinephrine to hand, dial 999 immediately.


    Triggers
    • Foods: especially nuts, some kinds of fruit, fish and less commonly spices

       

    • Drugs: Especially penicillins, anaesthetic drugs, some intravenous infusion liquids, and things injected during x-rays. Aspirin and other painkillers (called NSAIDs) can produce very similar reactions.

       

    • Latex: mainly in rubber latex gloves, catheters, other medical products, but also in many things encountered in daily life. Sufferers are nearly always health care workers, mainly nurses, or have other occupational contact with latex. They may get anaphylaxis from bananas, avocados, kiwi fruit, figs, or other fruits and vegetables including even potatoes and tomatoes.

       

    • Bee or wasp (yellow jacket) stings when these cause faintness, difficulty in breathing, or rash or swelling of a part of the body which has not been stung. If you just get a very large swelling of the part of your body which was stung, you are probably not going to have anaphylaxis if stung again.

       

    • Unknown: A substantial proportion of sufferers have no cause found despite all efforts, even in the most expert clinics. Doctors call such unexplained attacks 'idiopathic anaphylaxis' The word 'idiopathic' in practice means we don't know the cause. Worrying as it is, death from this is very rare indeed. However, there must be a cause or causes. Some cases are bound to be simple failure to find a cause and I always regard this diagnosis as provisional, but if a recognised allergy specialist has given you this label it is unlikely that another specialist will do any better. The explanation is NOT psychological in the vast majority. So in most cases this is a disease for which medical science has not yet discovered the cause. Some top experts who have studied hundreds of patients with idiopathic anaphylaxis believe that it is a disorder of mast cells, causing them to release histamine and chemicals with similar actions too easily. There is an excellent book on this condition, quite short, and intended for doctors and patients. Title: 'Idiopathic Anaphylaxis', edited by Roy Patterson, Published by OceanSide Publications Inc, Providence, Rhode Island, 1997, ISBN 0-936587-10-5.

       

    • Exercise may precipitate such reactions in some ('exercise-induced anaphylaxis'), and so may exercise after food, sometimes apparently irrespective of what the food is, but in other people after specific foods. This is called 'exercise-induced food-dependent anaphylaxis'.

       

    • Medicines called beta blockers used for heart disease or high blood pressure can change mild reactions from another cause into severe anaphylaxis because they block the body's main defence against anaphylaxis.

       

    • Wrong diagnosis of anaphylaxis: a proportion (about 10%) of people sent to specialists with a diagnosis of anaphylaxis have a mistaken diagnosis and have not had anaphylaxis. If this might be true in your case, it is well worth finding this out as you may be spared unnecessary fear and wrong treatment.

     


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    What helps?
    • Minimise the risk by taking great care and being vigilant. If you are food allergic, read labels like Sherlock Holmes: look for the "hidden" allergen. You can easily recognise a packet of peanuts but may miss the word "groundnuts" in tiny print on the side of a tin of curry sauce, or the Latin term arachis used to signify the presence of peanut in pharmaceutical products.
       
    • If you are food-allergic, be assertive about asking for detailed information from manufacturers and supermarket staff.
       
    • Be particularly careful in restaurants, where proprietors are under no obligation to list ingredients. Question staff very directly. It may be necessary to speak with a senior manager. Some restaurants have ingredient lists available for you to check. You may wish to telephone the restaurant in advance to ensure your allergy is taken seriously.
       
    • Be alert to all symptoms and take them seriously. Reach for the adrenaline (epinephrine) if you think you are beginning to show signs of a severe reaction. Do not wait until you are sure. Even if adrenaline is administered, you will still need to get to hospital as soon as possible. Someone must call an ambulance.
       
    • Make sure others in your family know how to administer the adrenaline kit - and when. Do not be frightened of adrenaline. It is a well-understood drug. The dose you will administer has very few side effects, which will pass quickly in any case. However, if you have heart difficulties, discuss these with your doctor.
       
    • Develop a crisis plan for how to handle an emergency. Get your allergist or GP to help. Have this written out for family and friends - put it on the bulletin board at home; carry one in your pocket. If a child is the person at risk, make sure his teachers and friends' parents have a copy - along with the adrenaline. Make sure everyone knows where the adrenaline is when you go out, or when you are at home.
       
    • Wear a Medic Alert talisman (details: 020 7833 3034).
       
    • Be open about your allergy problem with your family, friends and colleagues. It's easy to avoid a Thai, Chinese or Indian restaurant if everyone knows you are allergic to peanuts.

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    Medication

    The treatment for a serious allergic reaction is adrenaline (also known as epinephrine). During anaphylaxis, blood vessels leak, bronchial tissues swell and blood pressure drops, causing choking and collapse. Adrenaline (epinephrine) acts quickly to constrict blood vessels, relax smooth muscles in the lungs to improve breathing, stimulate the heartbeat and help to stop swelling around the face and lips (angioedema).
    Pre-loaded adrenaline injection kits are available on prescription for those believed to be at risk. These are available in two strengths - adult and junior. The injection must be given, as directed, as soon as a serious reaction is suspected and an ambulance must be called. If there is no improvement in 5-10 minutes, give a second injection.

    Because this must be administered without delay, patients known to be at risk often carry their own adrenaline injection kits for use in an emergency.

    The injection many doctors prescribe is the EpiPen, an easy-to-use device with a concealed needle. The EpiPen is available on prescription and distributed by ALK -Abelló, 2 Tealgate, Hungerford, Berkshire RG17 0YT. Tel 01488 686016.

    A relatively new adrenaline injection kit called the Anapen is also available on prescription. It is manufactured and distributed by Celltech Pharmaceuticals Ltd, 208 Bath Road, Slough, Berkshire SL1 3WE. Tel 01753 447690.

    Both companies provide trainer pens for practice purposes. For information on how to administer the EpiPen (click here) and Anapen, (click here).

    It is important to emphasise that even after adrenaline is administered, medical assistance should be sought urgently because the effects may wear off after 5 to 10 minutes and the injection may have to be repeated.

    In fact, doctors often prescribe more than one injection kit so that if medical assistance is delayed, patients may administer a second dose.


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    Statistics
    It is a sad fact that there are very few statistics available on Anaphylaxis related deaths in the UK. This makes it very difficult to gauge with any level of certainty, the effectiveness of treatments such as Epinephrine, or to evaluate how many individuals who are diagnosed as suffering from anaphylaxis suffer fatal attacks.

    More than one child in 100 is believed to suffer severe allergic reactions to peanuts, tree nuts or both. A small but significant number are affected by other foods.


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