Doctor insights on:
Third Generation Antihistamine
Which third generation antihistamine is best for itchy flaky scalp and skin levocetirizine, desloratadine or fexofenadine?
None of them!:
itchy scalp is due to irritation to the nerves of skin of the scalp. There is a nerve signal going from the scalp to the brain telling that there is something not right on the scalp. Correcting the local condition of the scalp such as dryness, scaling, seborrhea, bacterial or fungal overgrowth, and skin flaking condition will relieve the itch. Antihistamines are not useful for this. ...Read more
Yes: As far as we know, yes, they are safe to take long-term. ...Read more
Side effects: The second generation antihistamines were developed to try and decrease the side effects of the first generations. Many are "purified" first generation antihistamines so they have the active effects without the side effects of drowsiness, sedation, dry mouth etc. They also tend to have longer half lives, meaning they can be taken once or twice a day not every 4 hours. ...Read more
Difference between first and second generation antihistamines? Why are 1st generation considered nonsedating?
Sedation: 1st generation are sedating because many people, up to 40%, get sleepy when taking them. 2nd generation antihistamines are chemically modified and are less likely to cause sedation. The generics of the less sedating are cetirizine, fexafenadine, and loratidine. They cause sedation in some people, up to 11%, but much less than the older drugs. ...Read more
Are first generation antihistamines more effective than second generation? I always wonder why some are still on drugstore shelves, like chlorpheniram
Less side effects: There are many medications that remain on shelves for over-the-counter use that probably should be removed. New generation antihistamines are as effective as old ones. Of interest is that some individuals respond favorably to one over the other. The side effect profile and frequency of dosing is what really separates the new from the old antihistamines. In this case, newer is better. ...Read more
The 1st generation AH gets into the brain area thereby blocking the stimulatory effect on alertness from histamine. The 2nd generations ones do not get into the brain and thus do not usually induce drowsiness.
1st gen- more drying and better for runny nose, the sedating effect also better for itching than 2nd gen. ...Read more
Where can I find a reliable list of 2nd generation (and newer) oral antihistamines available in the US?
No long List: The newer oral nonsedating antihistamines available without prescription in the US are: loratadine (Claritin), fexofenadine (Allegra), cetirizine (Zyrtec) and levocetirizine (Xyzal). Desloratadine (Clarinex) is available by prescription. Some of the insurance medication plans will cover some of the above over-the-counter antihistamines. ...Read more
How can I safely test to see if an antihistamine produces drowsiness? I know even the new generation has this side effect.
Wait until a day: When you don't have to go to school (weekend) and try it. It's the only way to know. Take the smallest dose available and see if it works. ...Read more
Hi im at my wits end can you please help im a long term sufferer of urticaria on massive doses of second generation antihistamines and doxepin and?
Chronic urticaria: Chronic urticaria can be very difficult to manage, and requires a specialist. If you have already seen an allergist but s/he is not very gifted at managing severe hives, you may need a second opinion from another one. There are a number of allergists who do this across the country, but some are more comfortable with hard cases than others. You may need more labs or different medications ...Read more
What's the difference between a first generation antihistamine like chlorpheniramine and second generation antihistamines like allegra (fexofenadine)?
1st and second: First generation antihistamines are sedating and short acting and have usually other properties such as anticholinergic or drying properties. Second generation antihistamines are long aciting, usually dosed once a day, and are less or non sedating and selective antihistamines with less active properties on other receptors. ...Read more
Is antihistamines first generation effective drug for common cold and does vitamin c important during common cold?
Probably not: Antihistamines are effective for sneezing and runny nose due to allergies, by blocking histamine receptors, . but can over dry nasal passages during colds. Atrovent nasal spray helps runny nose and decongestants (use Short term only) help congestion. Vitamin C may help prevent colds, but not as effective once you have one. Rest, fluids, chicken soup, zinc, humidifier, and netipot help. ...Read more
What is the reason behind 1st generation antihistamine induce sleep (by which mechanism cause sleepiness in our brain)?
Anticholinergic: First generation antihistamines block the h1 and h2 histamine receptors but also have some anticholinergic effects by partially blocking other receptors. This can lead to dry mouth, urinary retention, sedation and other side effects. This is usually dose dependent and worsens with high doses. ...Read more
Is it bad to take an antihistamine during a cold, i.e. does suppressing mucus make the cold last longer?
No value: Antihistamines have no value in the treatment of viral illnesses. ...Read more
No: Antihistamines are a class of medication used since the 1940s. They are used to treat allergic conditions and are very safe. The newer generation antihistamines have even less side effects compared to first generation or old antihistamines. ...Read more
Taking lethal over: Dose would do that. Lethal overdoses of antihistamines are rare. Are you considering taking an overdose of antihistamines? If so, please get help right away. You can use national suicide hotlines 24/7 at 1-800-suicide (1-800-784-2433) or 1-800-273 – talk (1-800-273-8255). If you have accidentally taken too many antihistamines please contact 1-800-222-1222 (poison control hotline). Take care. ...Read more
New generation ones: Antihistamines in general are very safe. New generation products (Zyrtec, Claritin, (loratadine) Allegra, Xyzal) are just as effective with less side effects than older antihistamines (Benadryl, chlorpheniramine, hydroxyzine). However, it would be important to address WHY a person needs to take antihistamines long term? Consult with an allergist to assist in identifying the cause of symptoms. ...Read more
Yes: Butterbur has antihistamine-like effects. It can be found at health food stores. ...Read more
Yes: The drug will not affect the success of the vaccination or cause any negative reaction. ...Read more
New generation ones: The new generation antihistamines include Claritin, Zyrtec, Allegra and Xyzal (levocetirizine). These are as effective as older antihistamines (Benadryl, hydroxyzine, chlorpheniramine). Each person may respond differently to the different products and therefore trying them one at a time can be helpful. Since they are over-the-counter and generic (except for Xyzal (levocetirizine)), they are affordable and available. ...Read more
Which one: First generation antihistamines are sedating, second generation ones are not, overdosing on the latter hardly kills, but may cause sedation. Overdosing on first generation antihistamines may be more of a problem, but again they are safe in high doses. ...Read more
Unclear: Different antihistamines have different potencies. 10 mg of Zyrtec is equivalent to 180mg of Allegra (fexofenadine). Mg doseage as in all medicines are drug specific. In regard to toxic levels, each has it's own known limit. However too much antihistamine can lead to deadly arrythmias/ Please use the recommended dose. ...Read more
45-90 minutes: Antihistamines taken by mouth begin to work in about an hour but may take longer if you've just eaten. Antihistamine nasal sprays (astepro, patanase) begin to work in 30 minutes. An antihistamine injection, usually diphenhydramine, sometimes given for a severe allergic reaction or anaphylaxis begins to work in a few minutes. ...Read more