joe asked
I take Alavert daily for allergies and wanted to know if I could also use Benadryl during the day if my allergies are really bad or if I could just use it as a night time sleep aide?
Answer
In most cases, it is not recommended to take Alavert (loratadine) and Benadryl (diphenhydramine) together. There are however, some exceptions that are discussed below.
Taking Alavert And Benadryl Together
Both Alavert and Benadryl are antihistamine medications and work the same way mechanistically in the body. They both work by blocking histamine-1 receptors, preventing histamine from binding to it and producing allergy symptoms (e.g. runny nose, post-nasal drip, itchy eyes etc...).
As Alavert and Benadryl work the same way and are both classified as antihistamines, concurrent use of both is not recommended due to the increased chance of side effects and adverse reactions. Benadryl (diphenhydramine) by itself causes pronounced sedation and this sedation can be somewhat enhanced when combined with Alavert (loratadine), although Alavert is considered essentially non-drowsy when taken alone.
Having said all of the above, there are cases when both can be used together but first, a little on the differences between the two drugs.
Benadryl
Benadryl is known as a first generation antihistamine. The duration of action of the drug is typically 4-6 hours per dose (25 mg to 50 mg). The first generation antihistamines are known for their sedative effects and CNS depressant effects. Many patients cannot tolerate this drug except if it is given at bedtime due to the sedation it causes. Even then, some people experience a hangover effect the next morning. Due to this, Benadryl is a common ingredient in night time cold formulations since it is an effective sedative.
Alavert
Alavert contains the same active ingredient as Claritin, loratadine, although Alavert comes in a dissolving tablet form. Alavert is classified as a second generation antihistamine. Most second generation antihistamines are not associated with sedation, Alavert included. The only second generation antihistamine that is really associated with any sedation is Zyrtec (cetirizine).
Added Drowsiness
The interaction we are worried about is the additive drowsiness when Alavert and Benadryl are taken together. Although as mentioned above, Alavert is non-drowsy, combining it with another antihistamine that works the same way could potentially cause additive sedation. In addition, and perhaps most importantly, you probably would not get any additional benefit from taking the two together. Each drug on their own does a pretty good of blocking the histamine receptor and taking the two at once would not produce any appreciable difference from taking one alone.
One situation where it may be OK to take both close to each other is during an allergic reaction. It is thought that Benadryl is slightly more effective at stemming an anaphylactic reactions such as the reaction some people have to bee stings. The second generation antihistamines aren't thought to be quite as effective in these situations.
If you take Alavert on a daily basis for your seasonal allergies and were in a situation where you were having a serious allergic reaction, Benadryl may be an appropriate choice to add on before you make it to the hospital.
Lastly, Benadryl may be taking in the evening as a night time sleep aide. Generally, this use is okay and safe if you have taken Alavert earlier in the day. It is prudent however to start at a low dose of Benadryl to assess how you react. If you don't experience any adverse effects such as dizziness, dry mouth and dry eyes, you can continue taking Benadryl safely.
