Popular FAQ
Allegra vs Claritin: Which is more effective for allergies?
Both Allegra and Claritin are antihistamines but which one is more effective or has more side effects?
Allegra and Claritin are both second generation antihistamines with a low risk of sedation; however, Allegra has the lowest risk of sedation out of all antihistamines so is preferred if an antihistamine is needed for people working in safety-critical jobs.
Other differences:
- Studies point to Claritin being more effective than Allegra for allergic rhinitis (faster onset of action, more symptom relief)
- Allegra may provide more eye symptom relief.
- Studies suggest Allegra may be more effective than Claritin for wheal and flare reactions (an allergic skin reaction).
- Allegra should not be taken with grapefruit juice. Claritin has no reported food interactions.
Allegra is a brand name for the drug fexofenadine and Claritin is a brand name for the drug loratadine. Both fexofenadine and loratadine are popular antihistamines with many similarities but there are some important differences.
Which is more sedating? Allegra or Claritin?
Allegra (fexofenadine) and Claritin (loratadine) are second-generation antihistamines. Second-generation antihistamines were first developed in the 1990s to provide allergy relief without the unwanted side effect of sedation common to first-generation antihistamines such as promethazine and diphenhydramine.
Fexofenadine (Allegra), even in dosages exceeding those recommended, is the least sedating of all second-generation antihistamines, so is considered the antihistamine of choice for people in safety-critical jobs such as airline pilots. Loratadine (Claritin) is unlikely to cause CNS side effects such as sedation, or confusion when used at recommended dosages of 10mg/day; however, side effects may be more likely when used at higher dosages.
Which is more effective for Allergic rhinitis?
Trials have shown both Allegra (fexofenadine) and Claritin (loratadine) are significantly more effective than placebo (a pretend pill) for reducing symptoms associated with allergic rhinitis, hay fever, and other allergies. Trials have not consistently shown that one antihistamine is more effective than another; however, one trial reported loratadine had a quicker onset of action and provided more symptom relief in 836 patients with allergic rhinitis (Harold 2001). This result backed up a previous trial conducted in 2000 (Prenner et al).
Another trial reported fexofenadine as superior to loratadine at reducing ocular symptoms of rhinitis but similar to loratadine at reducing other rhinitis symptoms (Innes).
Intranasal or ophthalmic (into the eye) antihistamines have a quicker onset of action than oral antihistamines (within about 15 minutes); however, they need to be administered several times daily. In people with allergic rhinoconjunctivitis and predominantly eye symptoms, ophthalmic antihistamines work much quicker (within 3 to 15 minutes) and are much more effective than any other form of treatment. Intranasal antihistamines are as effective as intranasal cromolyn, intranasal nedocromil, and leukotriene modifiers in seasonal allergic rhinitis; however, are not as effective at relieving nasal congestion and other symptoms as intranasal glucocorticoids.
For urticaria and other skin reactions
All second generation antihistamines, including Allegra and Claritin, are effective for acute and chronic urticaria, although more trials have been conducted in people with chronic urticaria. No trial has consistently found one antihistamine to be better than another.
One trial reported that fexofenadine was superior to loratadine with regards to wheal and flare suppression (allergic skin reaction), with a faster onset of effect and a more effective suppression of the flare at each time point in the study (Kaliner et al).
Is it OK to take antihistamines every day?
Yes, most people can take antihistamines every day, if they have daily symptoms of their allergies. The number of times you take an antihistamine each day depends on the type of antihistamine.
Some antihistamines are taken every 4 to 6 hours, and some are longer-lasting antihistamines that are taken every 12 to 24 hours.
Consult the drug label and ask your health care provider how long and how often you should take an antihistamine.
How to take Antihistamines:
Occasional use when you have symptoms:
When you have an allergy that you only have occasionally you can take the antihistamine just when needed, once you have the symptoms.
Occasional use to prevent symptoms when you know your allergy triggers.
This is when you know you are going to encounter something that sets off your allergies, so you take your antihistamines as a preventative before you are exposed to the allergan that triggers your allergy.
Regular use for chronic allergies
You may take an antihistamine every day to keep long-term allergy symptoms under control.
Types of antihistamines
Second-generation antihistamine.
If you take an antihistamine frequently or daily, your health care provider may recommend a second-generation antihistamine as they are less likely to cause side effects like sleepiness and fatigue. Example of second-generation antihistamine are:
- Zyrtec (cetirizine)
- Xyzal (levocetirizine)
- Claritin (loratadine)
- Clarinex (desloratadine)
- Allegra (fexofenadine)
Second-generation antihistamines may be used to treat long-term conditions such as:
- Allergic rhinitis
- Sinusitis
- Atopic dermatitis
- Chronic urticaria
First generation antihistamines
The effects of first-generation antihistamines—such as Benadryl (diphenhydramine) or Chlor-Trimeton (chlorpheniramine), among others— they may cause drowsiness or sedation so are often taken at night.
These first-generation antihistamines are often used for short periods to treat or prevent:
- Common colds
- Seasonal allergies
- An allergic reaction
- Motion sickness
- Dizziness
Which antihistamines make you drowsy?
Older antihistamines, called first-generation antihistamines, may cause drowsiness, fatigue, and decreased alertness or concentration. These side effects are called sedation.
Examples of these drugs include:
- Benadryl (diphenhydramine)
- Chlor-Trimeton (chlorpheniramine)
Newer antihistamines are called second-generation antihistamines. They are less likely to cause sedation.
Examples include:
- Zyrtec (cetirizine)
- Xysal (levocetirizine)
- Claritin (laratodine)
- Clarinex (desloratadine)
- Allegra (fexofenadine)
Histamine is a natural substance of the immune system. It causes inflammation that can be an important part of your body’s defense against invaders like germs or viruses. Overreaction to histamine causes allergy symptoms and allergic reactions. All antihistamines block the effects of histamine, but first-generation antihistamines cross from the blood into the brain, called the blood-brain barrier. Because histamine also acts in the brain to help nerve cells communicate, antihistamines that cross the blood-brain barrier cause sedation.
Second-generation antihistamines are much less likely to cross the blood-brain barrier. Your doctor or pharmacist may suggest a second-generation antihistamine if you are treating allergy symptoms like a runny nose or an itchy rash.
However, if you are taking an antihistamine to treat motion sickness, relieve anxiety or use as a sleep aid, a first-generation antihistamine may be recommended due to the sedating effects.
There are many brands of antihistamines that are available over the counter (OTC), and finding the appropriate one for your needs can be confusing. Your health care provider may prescribe an antihistamine based on the symptoms or condition being treated. If you are taking an OTC antihistamine on your own, ask your pharmacist if it may cause sedation.
Can you take antihistamines when pregnant?
According to the American College of Obstetricians and Gynecologists (ACOG), several over-the-counter (OTC) antihistamines may be taken during pregnancy. Older, first-generation antihistamines can be taken, but they may cause drowsiness. Newer, second-generation antihistamines can also be taken and have less risk of drowsiness.
Oral decongestant medications should be avoided in the first three months of pregnancy.
Allergy or cold symptoms, allergic reactions, and allergic skin rashes may occur during pregnancy. You and your pregnancy care provider may weigh the benefits and possible risks of taking medication.
According to ACOG, the safest first-generation antihistamines for pregnant women are:
- Chlorpheniramine
- Dexchlorpheniramine
The American College of Allergy, Asthma, and Immunology (ACAAI) suggests Chlor-Trimeton (chlorpheniramine) as the first choice for pregnancy. ACAAI recommends two second-generation antihistamines if drowsiness is a problem:
- Claritin (loratadine)
- Zyrtec (cetirizine)
Both ACOG and ACAAI say to avoid OTC oral decongestants during your first three months of pregnancy due to a possible risk of abdominal wall birth defects. These include the decongestant Sudafed (pseudoephedrine) and other decongestants, such as phenylephrine and phenylpropanolamine.
Nasal spray for allergic rhinitis may be another option. Decongestant nasal sprays like Afrin and Neo-Synephrine appear to be safe in pregnancy, but can cause rebound nasal congestion if used for more than a day or two. Steroid nasal sprays may be more effective. ACAAI recommends starting with Rhinocort® (budesonide).
Always check with your pregnancy care provider before starting any OTC medication
