Like most antihistamines, there is not believed to be long term side effects. It is best if you consult a Dr before you take doses higher than usual. Read more Rebound to cessation of antihistamines would be unusual,.
Losing effectiveness is less well studied, but with ongoing use there could be some development of tolerance or it could be that you are still being exposed to an allergen and that is why symptoms are not controlled. If you took a combination antihistamine/decongestant, it would be more common.
However, you had been taking an antihistamine for 5 months. My hunch is that your nasal/sinus problem, for which you had taken the antihistamine in the first place, recurred the moment you stopped it. Read more Some antihistamines are more sedating than others.
Medications like Benadryl (diphenhydramine) can definitely cause sedation.
Unless, of course, the point is to see if Benadryl (diphenhydramine) will diminish the reactivity.
Good morning, itchy scalp is due to irritation to the nerves of skin of the scalp.
Short term sides effects are typically from older antihistamines such as Benadryl (diphenhydramine) that can cause drowsiness and delayed reaction time. Read more The side effects of antihistamines (dry mouth, tiredness. For example Benadryl (diphenhydramine) OTC is more likely to make you sleepy (in fact for some it's a safe sleeping pill) whereas the more recent additions to the OTC antihistamine group (eg Claritin) have less sleepiness (but more dry mouth) Each Person reacts differently to these drugs Try some Hope this helps DR Z ...
New generation antihistamines such as claritin, clarinex, zyrtec, xyzal and Allegra are generally very well tolerated. Read more Older antihistamines (AH) like Benadryl, (diphenhydramine) Atarax, Periactin caused drowsiness and dry mouth in at least 30% of the people. Newer antihistamines like Zyrtec, Xyzal causes drowsiness in about 10% of the people 3rd generation AH like Allegra and Claritin are not expected to cause drowsiness in 95% of the people. Read more New generation antihistamines (claritin, zyrtec, (cetirizine) allegra) will decrease itching, runny nose and sneezing associated with allergies. Older antihistamines do the same, but may also cause side effects like dry mouth, dry eyes, GI upset, fatigue, sleepiness, impaired reaction time, and increased appetite. Read more At night should not have any effect on how well they work the next day.
If you are using then as a sleep aid, will you need more with time to achieve the same level of sedation. A sympathetic nervous system stimulant that causes airways to dilate.
It is not an addiction, it is tolerance to the medication. Anti-histamines are not anticholinergic, per se, but in high doses or in the elderly they can cause some same neurological symptoms as anticholinergics.