People often look for the "best" of something, be it a television, a new car, or in this situation, the best over the counter allergy medicine. As is often the case, it is very difficult to classify something as the best as there typically are many different variables at play.
Are you looking for an antihistamine that is sedating to help you sleep or do you need something that will help your allergy symptoms without affecting your mental clarity? Are you looking to treat hives after eating the wrong food? Different situations call for different medications.
The good news is that we are here to provide a comprehensive list of all the over the counter antihistamines and provide detailed information to assist you in finding the best OTC antihistamine for YOU.
What Are Antihistamines For?
Antihistamines are the most common treatment for allergy symptoms resulting from allergic rhinitis, also known as allergic inflammation of the nasal airways. Allergic rhinitis can affect people either seasonally, known as seasonal allergic rhinitis, or all year round, known as perennial allergic rhinitis.
It has been reported that over 30% of adults and over 40% of children will be affected by allergy symptoms. The most common symptoms that patients complain of are sneezing, nasal congestion, runny nose, itchy and watery eyes as well as hives in more severe cases.
Although not completely understood why, the symptoms tend to be worse in the evening which can lead to troubled and restless sleep. Antihistamines taken by mouth are considered the best therapy for allergic rhinitis symptoms and are usually very effective.
Most antihistamines were at one point available only via a prescription but luckily, a vast majority of them are now available over the counter. In addition in their use for allergy symptoms, antihistamines are a common medication for insomnia.
We will discuss each antihistamine in detail, but first, let us simply list all of the available over the counter antihistamines based on their generation. As a general rule of thumb, the first generation antihistamines have been on the market a longest amount of time, last about 4-6 hours and cause sedation. The second generation over the counter antihistamines are newer, last about 24 hours and cause minimal to no sedation.
- Benadryl (Diphenhydramine)
- Dimetapp (Brompheniramine)
- Chlor-Trimeton (Chlorpheniramine)
- Tavist (Clemastine)
- Zyrtec (Cetirizine)
- Claritin (Loratadine)
- Allegra (Fexofenadine)
First Vs. Second
The second generation antihistamines offer the convenience of once daily dosing with little to no sedation. In fact, two of the second generation antihistamines, Allegra (fexofenadine) and Claritin (Loratadine), are completely non-drowsy.
Zyrtec (Cetirizine) is the only second generation over the counter antihistamine that is not marketed as completely non-drowsy. It has been reported that Zyrtec makes about 10% of people drowsy and as such, there is a warning on the box to not operate machinery while taking the medication. All of the first generation antihistamines cause drowsiness to some degree.
Onset & Duration Of Action
The onset of effect is very similar between both the first and second generation antihistamines. Commercials on TV for antihistamines are constantly trying to tout that their specific antihistamine is the best. The commercials for Allegra state, somewhat emphatically, that it works faster than Claritin for allergy symptoms.
However, a small disclaimer at the bottom of the ad clarifies that it applies to the first dose only. The reality is that most antihistamines work very similarly with consistent dosing. Some studies have shown that Allegra and Zyrtec may work SLIGHTLY faster than Claritin, however this usually is not significant when taking the medication for a longer period of time.
If one really wanted to rank the second generation antihistamines on how quickly they start to work, the ranking would be as follows: Allegra & Zyrtec are very similar followed by Claritin. The first generation antihistamines (e.g. Benadryl) are considered just as fast acting as Allegra and Zyrtec.
No matter how fast acting the antihistamines are, in order to get the best relief from allergies, it is important to take the medication before your allergy symptoms start. Antihistamines block the receptors that histamine (which causes the allergy symptoms) bind to. It is best to have those receptors already blocked when histamine rolls around to prevent the symptoms from starting.
All of the first generation antihistamines require multiple daily doses as they only last between 4 and 6 hours per dose. In contrast, all of the second generation antihistamines require only one dose per day. One recent study has shown however, that Zyrtec may by the longest lasting of the bunch. The study compared Allegra to Zyrtec and the results showed that Zyrtec had a longer duration of effect.
How Do Antihistamines Work?
Antihistamine medications block histamine from binding to receptors that are located all around the body. Histamine plays a central role in the allergic response. When histamine is released, it has a wide range of effects including:
- Vasodilation (dilation of the blood vessels) - Vasodilation causes the vast majority of the nasal symptoms you experience. Most commonly you become extremely congested but a runny nose is possible as well.
- Cardiac effects - Something we are not usually as aware of when our allergies hit us, but histamine influences both how hard our heart contracts and how fast it pumps.
- Contraction of Smooth Muscle - Smooth muscle is found everywhere in the body including in our airways. Histamine release causes the symptoms of wheezing and coughing.
- Itching - Histamine release also causes itching and redness. The mechanism behind this response is somewhat complicated, but it involves increasing the permeability of small vessels and the separation of skin cells.
Every OTC Antihistamine
The name Benadryl (Diphenhydaramine) is almost synonomous with the term allergy medicine. It was one of the first on the market over the counter and is still one of the most common.
It is not often used for daily allergy symptoms due to the excessive drowsiness it produces. In fact, more than 50% of people who take this medication have some sort of drowsiness with it.
For this reason, it is a popular night time sleep aid and is a component of many different brand name sleep medications. Benadryl (Diphenhydramine) is almost always the medication of choice to quell an allergic reaction to a food or other drug as it tends to be the most effective for hives and swelling. Each does lasts on average 4-8 hours.
Brompheniramine is an antihistamine that is not available by itself over the counter. It is only available in the drug Dimetapp, which is a combination of many different cough and cold medications.
It can produce drowsiness, but not to the extent as Benadryl does. Each dose lasts around 4-6 hours.
Chlor-Trimetron (Chlorpheniramine) is very similar to brompheniramine. It is however, available to purchase over the counter as a single ingredient.
It tends to be more effective for watery eyes and runny nose than even the second generation antihistamines like Claritin and Allegra due to it's drying effects. It does however, cause sedation in many patients, although much less so than Benadryl. Each dose lasts around 4-6 hours.
Tavist (Clemastine) is a hard drug to find nowadays over the counter. It is very similar to Benadryl in terms of how drowsy it makes people. Coupled that with the fact that each dose last around 12 hours, it doesn't have much use.
It tends to cause a hangover effect the next morning if used to induce sleep and it usually can't be taken during the day due to the sedation it causes. Still, it is a very effective antihistamine and it available for purchase in a few stores and online.
Like brompheniramine, this drug is typically not available the purchase by itself. Most people aren't aware of its existence but it is one of the most common antihistamines that is purchased over the counter as it is a component of the popular night time medicine Nyquil.
It is a very sedating antihistamine, right on par with Benadryl. It is added to Nyquil for its antihistamine effects and for the excessive sedation it causes.
The Best First Generation Antihistamine
First generation antihistamines can be very effective when they are used in the right situation. They are typically used for three different purposes:
As a sleep aid, Benadryl (Diphenhydamine) and dimenhydrinate are the most effective. They can both cause a hangover effect, but they on average only last 4-6 hours so it typically is not an issue as long as you plan on getting a full nights rest.
Allergic reactions to food or drugs
Benadryl (Diphendyramine) is the best choice here. It has the most evidence for benefit, and works better to reduce swelling and hives than other antihistamines.
Second-line options for seasonal allergies
Chlor-Trimetron (Chlorpheniramine) is a great second line option for allergy symptoms if the second generation antihistamines don't work well enough. While it may cause sedation and only lasts around 4 hours, it is not as sedating as many of the other first generation antihistamines and works exceptionally well for a runny nose and watery eyes.
Claritin (Loratadine) was the first of the second generation to go over the counter. It is the least expensive option of all the over the counter second generation antihistamines. It works for 24 hours and is completely non-drowsy. It is a great first choice medication for those looking for something to help with their allergy symptoms. Even though studies have shown that the other antihistamines may work faster, it only applies to the first few doses and is fairly insignificant.
Zyrtec (Cetirizine) was the second of the second generation antihistamines to go over the counter. As with Allegra and Claritin, each dose lasts 24 hours. The main drawback of Zyrtec is that it does cause drowsiness and sedation in about 5-10% of people. It is not marketed as non-drowsy. It has about the same effectiveness as Claritin and Allegra although it may work slightly faster than Claritin. It usually is priced right in between Allegra and Claritin.
Allegra (Fexofenadine) was the last of the second generation antihistamines to go over the counter. It is also a 24 hours acting antihistamine and is completely non-drowsy. Studies have also shown that it may be the fastest acting antihistamine. It is great choice for those in which Claritin does not work well enough. It unfortunately is the most expensive option however.
The Best Second Generation Antihistamine
All of the second generation antihistamines are available over the counter as generic products at a greatly reduced price from their brand name counterparts. In terms of cost, Claritin (loratadine) is the least expensive and Allegra (fexofenadine) is the most expensive.
Since most patient are looking for an allergy medicine that is completely non-drowsy, Claritin and Allegra top the list as the best over the counter allergy medicines. For a first time allergy medication user, Claritin is the most highly recommended due to the price, duration of action and absence of sedation as a side effect. If Claritin doesn't work well enough, Allegra is the next best option