Synonyms and Keywords:-
drug allergy, allergen, allergic reaction, anaphylactic shock, anaphylaxis, antibodies, antibody, hypersensitivity, medication allergies, medication reactions, immune system, immunoglobulin E, IgE, serum sickness
Description:
A drug allergy is an allergy to a drug, most commonly a medication. Medical attention should be sought immediately if an allergic reaction is suspected....CLICK & SEE
An allergic reaction will not occur on the first exposure to a substance. The first exposure allows the body to create antibodies and memory lymphocyte cells for the antigen. However, drugs often contain many different substances, including dyes, which could cause allergic reactions. This can cause an allergic reaction on the first administration of a drug. For example, a person who developed an allergy to a red dye will be allergic to any new drug which contains that red dye.
A drug allergy is different from an intolerance. A drug intolerance, which is often a milder, non-immune-mediated reaction, does not depend on prior exposure. Most people who believe they are allergic to aspirin are actually suffering from a drug intolerance.
Both over-the-counter and prescription drugs can cause various problems. Most symptoms, such as nausea and diarrhea, are not allergies but side effects that can affect anyone. A drug allergy occurs when the immune system produces an abnormal reaction to a specific drug. Often the reactions are mild, but some can be life-threatening.
Several different types of allergic reactions to medications can occur. Reactions to drugs range from a mild localized rash to serious effects on vital systems. The body’s response can affect many organ systems, but the skin is the organ most frequently involved.
It is important to recognize the symptoms of a drug allergy, because they can be life-threatening. Death from an allergic reaction to a medication is extremely rare, however.
An allergic reaction does not often happen the first time you take a medication. A reaction is much more likely to occur the next time you take that medication. If you have a reaction the first time, you probably were exposed to the medication before without being aware of it.
Causes:
An allergic reaction is caused by the body’s immune system overreacting to the drug, which is viewed as a chemical “invader,” or antigen. This overreaction is often called a hypersensitivity reaction.
*The body produces antibodies to the antigen and stores the antibodies on special cells.
*The antibody in an allergic reaction is called immunoglobulin E, or IgE.
*When the body is exposed to the drug again, the antibodies signal the cells to release chemicals called “mediators.” Histamine is an example of a mediator.
*The effects of these mediators on organs and other cells cause the symptoms of the reaction.
The most common triggers of drug allergies are the following:
*Painkillers (called analgesics) such as codeine, morphine, nonsteroidal antiinflammatory drugs (NSAIDs, such as ibuprofen or indomethacin), and aspirin
*Antibiotics such as penicillin, sulfa drugs, and tetracycline
*Antiseizure medications such as phenytoin (Dilantin) or carbamazepine (Tegretol)
Symptoms:
Drug allergies may cause many different types of symptoms depending on the drug and the degree of exposure to the drug (how often you have taken it). These are the most common reactions:
Skin reactions:
A measles-like rash
Hives—Slightly red, itchy, and raised swellings on the skin, which have an irregular shape
Photoallergy—Sensitivity to sunlight, an itchy and scaly rash that occurs following sun exposure
Erythema multiforme—Red, raised and itchy patches on the skin that sometimes look like bull’s-eye targets and which may occur together with swelling of the face or tongue
Fever
Muscle and joint aches
Lymph node swelling
Inflammation of the kidney
Unlike most allergic reactions, which occur fairly quickly after exposure to the allergen, allergic reactions to drugs tend to occur days or weeks after the first dose of the drug.
Anaphylaxis or anaphylactic reaction—This is a serious allergic reaction that can be life threatening. A person with anaphylaxis must be treated in a hospital emergency department. Characteristics of anaphylaxis (sometimes referred to as anaphylactic shock) include:
Skin reaction—Hives, redness/flushing, sense of warmth, itching
Difficulty breathing—Chest tightness, wheezing, throat tightness
Fainting—Light-headedness or loss of consciousness due to drastic decrease in blood pressure (“shock”)
Rapid or irregular heart beat
Swelling of face, tongue, lips, throat, joints, hands, or feet
Almost all anaphylactic reactions occur within four hours of the first dose of the drug. Most occur within one hour of taking the drug, and many occur within minutes or even seconds.
An allergic reaction to a drug may give rise to the following symptoms:
If you develop the symptoms and suspect they may be due to a prescription, or over-the-counter drug, contact your doctor at once before taking the next dose. Rarely, a drug allergy may lead to a severe and potentially fatal reaction called anaphylaxis.
Risk factors for drug allergies include the following:-
*Frequent exposure to the drug
*Large doses of the drug
*Drug given by injection rather than pill
*Family tendency to develop allergies and asthma
*Certain food allergies such as to eggs, soybeans, or shellfish
When to Seek Medical Care:-
Always contact the health-care provider who prescribed the medication for advice.
*If the symptoms are mild, such as itching and localized hives, the provider may switch you to a different type of medication, recommend that you stop the medication, or, if appropriate, prescribe antihistamines to relieve your symptoms.
*If you cannot reach this provider for advice quickly, play it safe and go to a hospital emergency department.
*If you are having any “systemic” symptoms such as fever or vomiting, you should stop taking the medication and be seen immediately by a medical professional.
*If you are having difficulty breathing, your throat is swelling, or you are feeling faint, you may be having an anaphylactic reaction. Go immediately to a hospital emergency department. Do not attempt to drive yourself. If no one is available to drive you right away, call 911 for an ambulance. While waiting for the ambulance, start self-treatment.
Diagnosis:-
Generally a drug allergy is identified by signs and symptoms. Medical professionals are trained to recognize hives, swelling patterns, and rashes associated with allergic reactions. You will be asked questions about your medical history and possible triggers of the reaction.Blood tests and other tests are needed only under very unusual circumstances.
Treatment:-
After getting advice from your health-care provider, some mild allergic reactions may be treated at home.In very serious cases only , Hospitalization may be required.
Self Home Care:-
For hives or localized skin reactions, perform the following:
*Take cool showers or apply cool compresses.
*Wear light clothing that doesn’t irritate your skin.
*Take it easy. Keep your activity level low.
To relieve the itching, apply calamine lotion or take nonprescription antihistamines, such as diphenhydramine (Benadryl) or chlorpheniramine maleate (Chlor-Trimeton).
For more severe reactions, self-treatment is not recommended. Call your health-care provider or 911, depending on the severity of your symptoms. If you have symptoms of anaphylaxis, here’s what you can do while waiting for the ambulance:
Try to stay calm.
*If you can identify the cause of the reaction, prevent further exposure.
Take an antihistamine (one to two tablets or capsules of diphenhydramine [Benadryl]) if you can swallow without difficulty.
*If you are wheezing or having difficulty breathing, use an inhaled bronchodilator such as albuterol (Proventil) or epinephrine (Primatene Mist) if one is available. These inhaled medications dilate the airway.
*If you are feeling light-headed or faint, lie down and raise your legs higher than your head to help blood flow to your brain.
*If you have been given an epinephrine kit, inject yourself as you have been instructed. The kit provides a premeasured dose of epinephrine, a prescription drug that rapidly reverses the most serious symptoms.
Bystanders should administer CPR to a person who becomes unconscious and stops breathing or does not have a pulse.
If at all possible, you or your companion should be prepared to tell medical personnel what medications you take and any known allergies.
Modern Medical Treatment:-
Generally, treatment of a drug allergy falls into three categories:
Mild allergy (localized hives and itching)
Treatment is aimed at caring for the symptoms and stopping the reaction caused by the drug.
Medications prescribed may include antihistamines, such as diphenhydramine (Benadryl)
You may be advised to stop taking the medication that caused the allergy.
Moderately severe allergy (all-over hives and itching)
Treatment is aimed at caring for the symptoms and stopping the reaction.
Usually the offending medication is stopped.
Medications prescribed may include antihistamines such as diphenhydramine (Benadryl)), oral steroids (prednisone), or histamine blockers such as cimetidine (Tagamet), famotidine (Pepcid), or ranitidine (Zantac).
Severe allergy (shortness of breath, throat tightness, faintness, severe hives, involvement of many organ systems)
Treatment includes strong medications to quickly reverse the dangerous chain of events.
The offending medication is stopped immediately.
Medications prescribed may include antihistamines such as diphenhydramine (Benadryl), oral or IV steroids such as prednisone or methylprednisolone (Solu-Medrol), or histamine blockers such as cimetidine (Tagamet), famotidine (Pepcid), or ranitidine (Zantac).
Depending on the severity of other symptoms, other medications may be used including epinephrine (also called adrenaline), which is inhaled, given by IV, or injected under the skin.
If your reaction is severe, you may need to be admitted to the hospital for continued therapy and observation.
Follow-up:-
Follow up with your health-care provider after an allergic reaction to a drug. At this follow-up appointment, he or she can evaluate your recovery from the reaction and adjust any medications.
If you do not respond to the treatment prescribed for your drug allergy, it is important that you see a medical professional for re-evaluation.
Ayurvedic Treastment : VIRECHAN
Prevention:-
There is no known way to prevent drug allergies. You can reduce your risk by taking as few medications as possible. The more exposure your body has to medications, the greater the likelihood of a drug allergy.
Always tell any new health-care provider you see about your allergies and the types of reactions you have had. Talk to your doctor about the possibility or necessity of having a portable epinephrine kit to treat severe reactions.
Do not take a drug that you have reacted to in the past. Once you have a reaction to a drug, your risk of having a more severe reaction next time increases dramatically.
Consider wearing a medical alert ID bracelet or necklace. These devices are worn on the wrist or neck and can alert medical personnel and others about the risk for an allergic reaction.
Adults might carry a card with pertinent medical information in a wallet or purse. Tell your health-care provider about any adverse reactions to medications in the past before he or she prescribes medications to you.
Tell your health-care provider about any medications, prescription or over-the-counter, that you are taking.
Click for->Practice Guidelines: Drug Allergy
Resources:
http://en.wikipedia.org/wiki/Drug_allergy
http://www.emedicinehealth.com/drug_allergy/page15_em.htm
http://www.charak.com/DiseasePage.asp?thx=1&id=246
