Doctor insights on:
Second Generation Antihistamines
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 moreSee 2 more doctor answers
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
CNS: 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 moreSee 1 more doctor answer
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
Whats 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 moreSee 1 more doctor answer
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
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
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 moreSee 2 more doctor answers
Which third generation antihistamine is best for itchy flaky scalp and skin levocetirizine , desloratadine or fexofenadine ?
None of them!: Good morning, 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
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
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