Treat Allergies. What is an antihistamine, and allergy symptoms

What is an antihistamine?

Antihistamines work to reduce allergy symptoms by blocking the release of a natural chemical known as histamine. When you have an allergy, you body mistakenly releases histamine in response to a benign foreign substance, an allergen, that it mistakes for a threatening antigen. Typically, histamine produces sneezing, itchy eyes, a runny nose and rashes (usually hives). By reducing the amount of histamine in the body, antihistamines can alleviate these symptoms but they cannot treat the cause of the allergy.

Is it true that antihistamines should not be taken by asthmatics?

No, this is not the case at all. In fact, because of the increased risk of asthma for those who have hayfever, there is every reason for an asthmatic to use antihistamines to control their hayfever. Second generation antihistamines like Zyrtec and Claratyne (Claritin) have been shown to have no detrimental effect on asthma and can actually improve the condition.

The belief that antihistamines should not be taken by asthmatics was actually based on some studies using first generation antihistamines. These led to the assertion that antihistamines could increase an asthmatic's asthma symptoms or their decrease lung function. This is certainly not true of the second generation antihistamines now available.

When should I take an antihistamine-decongestant combination product?

If an antihistamine works in treating the other symptoms of your allergy and you have congestion then a combination product can help. Antihistamines alone will not relieve congestion.

What is the "rebound effect" when using a decongestant?

Decongestants are useful in reducing the swelling within the nose but they are not intended for use over an extended period of time. If you use them for more than three days in a row, you may develop what is known as the "rebound effect" which can make nasal swelling even worse. Increasing the dosage or using the spray more frequently in response to this can lead to a condition called "rhinitis medicamentosa", where a sufferer alternates between decongestion and rebound swelling.

When should I start taking an antihistamine?

If your allergy is seasonal, then the best idea is to take an antihistamine before the season begins. Allergy medications are better at preventing symptoms before they develop rather than treating those that are already present in the system. For example, nasal corticosteroids like Beconase, Butacort 50, and Flixonase are usually more effective if taken two weeks before the start of the allergy season because it can take a week or two for them to reach their maximum effectiveness. Allergy medications are also more effective if they are taken on a regular schedule during the allergy season. If you have a perennial allergy then you can take antihistamines or nasal corticosteroids all year round for relief.

Will taking antihistamines make me drowsy?

The new non-drowsy, non-sedating antihistamines including Claratyne (Claritin), Zyrtec, Claramax (Clarinex) and Telfast (Allegra) are second generation antihistamines that rarely cause any drowsiness. If they do cause you to feel drowsy, do not drive or operate heavy machinery while affected.

How can I tell if it an allergy and not just a cold?

While the symptoms of allergies and colds are similar, there are some ways to tell them apart. One is the order in which the symptoms occur. With a cold, it is common to only have one symptom at a time, starting with sneezing, and followed by a runny nose and congestion. With an allergy, all symptoms can occur all at once.

Another feature is the duration of the symptoms. The symptoms of a cold will only last about a week to ten days but an allergy will continue to produce symptoms as long as the sufferer is exposed to the allergen. Also, consider the time of year that the symptoms developed. Colds are more common during the winter months, whereas allergies are more commonly encountered from spring through to autumn when most pollen is released.

While a cold typically produces a yellowish nasal discharge suggesting an infection, allergies tend to result in a clear and watery discharge of mucus from the nose. Add to this the fact that sneezing is more commonly a symptom of an allergy, especially when they occur in clusters of two or three in a row. While colds are often accompanied by a fever, this is not a feature of allergies.

Will my children inherit my asthma or allergies?

While not strictly hereditary, there is a genetic predisposition for children to develop allergies if their parents have them. Chances are that, if both parents are allergic, the tendency to be allergic will be passed down to the children. Of course, the children may not develop any allergies but if one parent is allergic then it has been estimated that a child has about a 50% chance of having allergies, a risk that increases to around 75% if both parents have allergies. What this means is that the child inherits a tendency to be allergic, but does not inherit the reaction to a specific allergen because the manifestations of the allergy are different. The allergy will not develop until the child is exposed to a particular allergen. If a parent has an allergy to dogs or has asthma, the child may develop a different sort of allergy, such as hayfever or an allergy to mould. This is why, if you have allergies, it is a good idea to try to limit a child's exposure to common indoor allergens. This is also why families with allergies do not always have allergies to the same things.

How is an allergy diagnosed?

Your doctor can diagnose if you have an allergy. After discussing your medical history and giving you a physical examination, the doctor can use skin tests to determine what you are allergic to. During the skin test, extracts of different types of allergens are used to scratch or prick the skin. If there is a reaction to that substance then this suggests an allergy exists.

I am due to have skin tests. Should I stop taking my antihistamine?

Yes. Because antihistamines can interfere with the results of the test, you should discontinue using an antihistamine about 48 hours before the test is scheduled.

Should I get tested to see if I am allergic to insect stings?

There is probably little point in being tested for an insect allergy unless you have been stung and have had a reaction to it because there are so many different types of insects that can cause an allergy. It would be helpful if you can identify the insect that stung you but even if you cannot, the doctor or allergist should be able to work out what type of insect caused the reaction.

How can I tell whether or not I have asthma?

Your doctor can diagnose whether you have asthma. They will take into account a number of factors, including typical symptoms, your medical and family history, and a physical exam that often includes breathing tests.

Is it safe to use antihistamines during pregnancy?

It is generally recommended that you do not take drugs during pregnancy, including second generation antihistamines like cetirizine and loratadine. There are, however, no clinical studies that have established an incontrovertible link between antihistamines and major birth defects, specifically in the first trimester of pregnancy. Because there is no data to suggest that antihistamines cause harm to the mother or the foetus, in special cases antihistamines have been prescribed for severe urticaria in pregnant women. If you are pregnant and feel that you need to use an antihistamine, you should consult with a qualified medical practitioner before beginning treatment.

Is it safe to take antihistamines while breast-feeding?

It is best to be cautious about taking antihistamines while breast-feeding. Most antihistamines represent only a minimal risk to a breastfeeding mother and child, and antihistamines that are taken nasally rather than orally have even less chance of being transferred to a mother's milk. Antihistamines can possibly reduce milk production because antihistamines tend to decrease bodily secretions and could result in an infant becoming drowsy if the medications pass into the breast milk, even if the amount present is only about 1% of the adult dosage. It is not recommended that babies be exposed to antihistamines because they are more susceptible to the side effects, including irritability or overexcitement, but it is not known whether second generation antihistamines cetirizine or loratadine share these side effects. The safe use of loraratine, for example, has not been established during pregnancy, lactation or in infants under one year of age. Antihistamines should not be taken in the early postpartum weeks or by mothers who already have a compromised milk supply.

Can I still drink alcohol while taking antihistamines?

Most second generation (non-drowsy) antihistamines do not place a restriction on the consumption of alcohol during treatment. Read the instruction that come with each product or check with your doctor regarding a particular medication. Obviously, if you find that the "non-drowsy" antihistamines make you drowsy then you my need to limit your alcohol intake while you are taking these.

Will moving to another part of the country solve my allergy problems?

It is not necessarily true that moving to another geographic location with a different climate will improve your allergy symptoms. If you are susceptible to allergies then you may eventually develop a new or related allergy to the pollen of the plants in the area you have moved. Remember that airborne pollen can travel quite long distances, with some pollens being encountered a far as 400 miles out to sea. Other airborne allergens, such as dust or mould, are going to be present in almost any indoor environment so moving is unlikely to help you if you have perennial rhinitis.

What is animal dander?

Animal dander is a common allergen. The oil glands in an animal's skin secrete proteins, which are also found in its saliva, that can cause an allergic reaction in some people. Animal dander consists of the hair, fur and dry skin that an animal has shed that contain these proteins. The symptoms of an allergy to animal dander include the usually indicators of an allergy, including sneezing, itchy and watery eyes, and congestion. They may continue for a considerable time after contact with the animal.