Antihistamines 101: What to use & when!

Mar 21, 2012

By Barret Procyshyn, Pharmacist at the Dauphin Clinic Pharmacy


A very important area in the front store of a pharmacy is the antihistamines section or the area will all of our allergy products. It is also a very big area and it seems as though there are new products being added every day. It can be a little confusing when trying to choose the best product for you. While you should always consult your pharmacist before trying an antihistamine for the first time, here are some recommendations.


If you suffer from allergic rhinitis, which includes runny nose, sneezing, itching and watery eyes; an oral antihistamine is likely the best product for you. Often we confuse seasonal allergies for a common sinus cold or flu. The easiest rule is if your mucous is somewhat clear or your eyes are watery and itching, allergies are to blame. Remember if you are prone to allergies take the medication before the symptoms arrive rather than treating them as they develop. You will have much more symptom control. For example, if you notice seasonal allergies arrive when the grass starts growing, start taking an antihistamine a week or two before this would normally occur. If you time it right you may not notice any seasonal allergies at all.


Oral antihistamines are divided into two classes; 1st and 2nd generation, both having very similar effectiveness. The first generation which includes Benydryl, may cause some drowsiness, work impairment or slow reaction time. For this reason we almost always recommend the 2nd generation such as Reactine, Claritin or Aerius. Another benefit to 2nd generation is they usually only need to be dosed once per day. Most antihistamines are available as store brand products. These products are much cheaper than the name brand product and use the exact same medical ingredients, so they are a product I highly recommend.


It is important to note while antihistamines dry the running nose, they do not have a decongestant effect. You can either find a tablet with an antihistamine and decongestant combination or you can use a decongestant spray. Oral decongestants should be the first choice, but their use in someone with high blood pressure or other related health issues can be dangerous. Decongestant sprays can and will cause re-bound congestion if used for more than three days, so caution must be used. Always consult a pharmacist before selecting a product with decongestants.


Another reason to visit the antihistamine area is for a rash or skin irritation. If the rash is localized we will sometimes recommend a mild steroid cream or a topical antihistamine. Benedryl cream is the most common, is fairly safe and does a good job of reducing the reaction and any itching which may be present. It is also a good option for mosquito bites if you are susceptible to reacting to them. If the rash is on a significant portion of the body, for example on two arms or across the back, I usually recommend an oral antihistamine. Remember it is always important to consult with your physician to find out what you are reacting to.


The best oral antihistamine for a rash is probably a first generation antihistamine like diphenhydramine. The first generation pills seem to be working faster than something like Reactine or Claritin. I would also recommend these products for mild bee sting reactions and mild hive breakouts, because you want to treat the reaction quickly. Remember, diphenhydramine and other medications in its class can make you drowsy so be cautious and consult your pharmacist if you have any questions.


Remember if you have severe allergies which could cause anaphylaxis: which includes trouble breathing, anxiety, palpitations and hives covering the body, you need to carry an Epi Pen just in case. No pill or cream can treat an anaphylactic allergic reaction.


If you suffer from seasonal allergies be sure to treat them ahead of time so you can enjoy springtime. When selecting an antihistamine remember your pharmacist can help find the best product for you.


As always if you have any questions or concerns about these products, ask your pharmacist.

The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

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