Brief Answer:
It is recommended not to exceed 10 mg of
Zyrtec per day.
It should be avoided usage of
Cetirizine together with
Benadryl , because side effects may be increased.
Detailed answer:
Hello,
Thank you for using HCM.
It is not recommended to take 20 mg of Zyrtec per day. If you take a higher dosage of it you may feel restless or nervous, and then you may feel drowsy.
You can keep taking both Zyrtec 10 mg per day and Montelucast, because there are no proven interactions between them. But, using Cetirizine together with Benadryl may increase side effects such as
dizziness,
drowsiness, and difficulty concentrating. So , you can use Zyrtec + Montelucast or Benadryl + Montelucast. The recomended dosage of Benadryl is 25 to 50 mg orally every 4 to 6 hours as needed, not to exceed 300 mg/24 hours.
Drinking alcohol can increase certain side effects of Zyrtec.
You can experience sleepiness, or somnolence, when taking Zyrtec or Benadryl, so do not drive a car, while taking one of them.
Hope this is helpful.
Let me know if you need more clarifications. Otherwise please close and rate the answer.
Kind Regards,
Dr. Juarda