Sorensen Debbie asked
Can you take clemastine and Allegra together?
Answer
Clemastine (Tavist) and fexofenadine (Allegra) are both
considered to be antihistamine medications. Antihistamines are widely used for
self-care of allergy symptoms including runny nose, watery eyes, sneezing, and
itching of the nose, throat, or eyes. Clemastine
is considered to be a first-generation antihistamine which are generally
known to be more sedating than the second-generation class of antihistamines. Allegra is a part of the second-generation
class of antihistamines and is therefore less likely to cause drowsiness. Because clemastine and Allegra are both
antihistamines, it is not recommended to take them together since they both
work in the same way and could increase your risk of antihistamine related side
effects.
How Antihistamines Work
Antihistamines bind to histamine receptors that are found in the nose, lungs, eyes, and skin without activating the histamine response. By binding and changing the shape of the histamine receptor, antihistamines inhibit histamine from binding and creating its response. Histamine creates an immune response to essentially attempt to remove the offensive allergen.
Histamine can be triggered by a variety of things including pollen, dust, and pet dander. Some people are more sensitive to this response and may not even know what triggers their allergies. Antihistamines are useful in preventing the immune cascade so common in people suffering from allergies.
First-Generation Antihistamines
First generation antihistamines include diphenhydramine (Benadryl), chlorpheniramine (Chlor-Trimeton), clemastine (Tavist), promethazine (Phenergan), and others. These medications cross the blood-brain barrier and have CNS effects like drowsiness and dizziness. First generation antihistamines can also cause urinary retention, GI upset, and blurry vision.
The first generation antihistamines are also listed as
medications to avoid in elderly adults by the Beers Criteria
due to the increased risk of confusion, dry mouth, and drowsiness.
Second Generation Antihistamines
Second generation antihistamines include fexofenadine (Allegra), loratadine (Claritin), and cetirizine (Zyrtec). These are generally non-sedating, however, both loratadine and cetirizine have been shown to cause at least some drowsiness. Fexofenadinecan cause headache, vomiting, upset stomach, and dizziness. Because of the increased risk for side effects like dizziness, it is not recommended to take multiple antihistamines at the same time.
Clemastine usually lasts
about 10-12 hours and it would be lower risk to take Allegra after that time. Allegra
typically lasts up to 12 hours as well.
When taking fexofenadine (Allegra) it is important to avoid grapefruit, orange, and apple juice as these are known to decrease intestinal absorption. Avoid these juices at least 4 hours before and 2 hours after taking Allegra.
