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Reviewed by Antihistamines and decongestants are commonly used for symptomatic relief from allergies and colds. Although both drugs may be used singly or together for these purposes, they do not work the same way. This article discusses the similarities and differences between these cold medicines with their respective pros and cons.
Table of Contents
Are Antihistamines and Decongestants the Same?
Antihistamines vs. Decongestants: Although both drugs are used in the treatment of a common group of illnesses (colds, allergies), both drugs are not the same. The drugs have different modes of action and produce different results but are often mistaken for each other because they produce a few similar results.
What does an antihistamine do? As the name implies, this group of drugs that work by inhibiting the actions of a chemical called histamine. Histamine is released during an allergic reaction. In a person who is allergic to a particular agent; dust, pollen, fumes, etc., re-exposure to the allergen causes the immune cells to stimulate the release of histamine. Histamine produces the symptoms of allergies such as a runny nose, nasal congestion, nasal itch, and teariness of the eyes.
Antihistamine foods, such as bell peppers, broccoli, red wine, and citrus fruits also produce a similar result. These foods have natural anti-histamine agents and may be used as antihistamine alternatives for home remedies.
Decongestants, on the other hand; and as the name implies, decongest the nostrils, sinuses, and airways which are clogged with mucus when one has colds and symptoms of flu. These drugs work by constricting blood flow in these areas, consequently reducing mucus production. This allows mucus to drain correctly.
Similarities Between Nasal Decongestants and Antihistamines
Both classes are drugs are alike in a few ways;
- Uses: Both antihistamines and decongestants can be used in the treatment of colds, allergies, and flu. While decongestants may provide relief of nasal congestion and breathing problems, antihistamines take care of those and the other symptoms including runny nose, sneezing, watery eyes, nasal and eye itch, and postnasal drip.
- Formulations: Both drug classes are available in the same formulations; as oral drugs, nasal sprays, eye drops, and are contained in several expectorants.
- Contraindications and complications: Antihistamines and nasal decongestants have similar contraindications; Both classes of drugs should be avoided by individuals who have high blood pressure, an overactive thyroid gland, enlarged prostate, and heart disease.
Differences Between Antihistamines and Decongestants
What is the difference between a decongestant and an antihistamine? Though both are thought of as similar, these two classes of drugs have a lot of differences. These are outlined in the table below.
| Differences | Decongestants | Antihistamines |
|---|---|---|
| Mode of Action | Decongestants work by constricting the blood vessels, thereby reducing fluid buildup in the nostrils and airways. | These work by blocking the effects of histamine. This not only includes the nasal and airway congestion but other allergy symptoms |
| Effects | Provide relief only from nasal and airway swelling and congestion in colds. | Produce relief of other symptoms of colds and allergies other than nasal congestion; such as cough, runny nose, teary eyes, red eyes, sneezing, as well as itchy nose and eyes. |
| When to take antihistamine vs. decongestant. | Used typically for relief from colds and nasal allergies. | Used for all types of allergies, not just nasal allergies. |
| Risk of Rebound Symptoms | Prolonged use (more than 3-5 days) causes the symptoms to rebound, in a condition called rhinitis medicamentosa. | Do not cause rebound cold symptoms. (But what happens if one takes too much antihistamine? It may cause fast heart rate, cardiac arrest, and in severe cases, death.) |
| Prophylaxis | These can not protect from symptoms if used before the onset of symptoms. | Oral antihistamines can prevent allergic symptoms if taken before the onset of symptoms. |
| Use in breastfeeding | Decongestants such as phenylephrine and pseudoephedrine can reduce breast milk so should be avoided. | Antihistamine breastfeeding is not a contraindication. |
| Examples | Pseudoephedrine, Phenylephrine, oxymetazoline | Benadryl, Cetrizine, and Fexofenadine. |
Antihistamines Vs. Decongestants: Which is More Effective?
There is no straight answer to this question. Deciding which of these drugs is better for an individual depends on several factors including the nature of the symptoms, tolerance to the side effects of each, and one’s health status.
If one only has to deal with nasal or sinus congestion, a decongestant without antihistamine will be appropriate. But to deal with other symptoms such as a runny nose, sneezing, nasal itch, and watery eyes, use an antihistamine.
Nonetheless, the varying side effects of these drugs may also influence this decision to take either of the medications. Decongestants may cause a slight feeling of restlessness and hyperalertness with a fast heartbeat. If an individual can’t deal with any of these, it may be best to take an antihistamine. Conversely, some over-the-counter antihistamines cause drowsiness, and if an individual does not want this, decongestants or non-sedating prescription antihistamines may be better.
Furthermore, an individual’s health status and other medicines one takes may also influence this decision. Both drugs may cause adverse interactions when used with other medications and may even exacerbate certain conditions if used singly.
In summary, there is no single answer to the question which is better between antihistamines and decongestants, simply speak with a physician before using any of them.
Combinations of Antihistamines and Decongestants: Are they Safe?
Can one take an antihistamine and decongestant together? Yes, and there are many such combinations on the market. The rationale behind these combinations is to offer the synergistic or additive effects of both classes of drugs. Instead of using them singly, why not combine them in one pill?
These antihistamine decongestant combos are entirely safe to use but have contraindications which are always spelled out on the label of the drugs. Common side effects of these drugs include fast heartbeat, drowsiness, and headache.
Examples of these antihistamine decongestant combinations include Bromfed-PD, Allegra-D, Aldex-D, and Ceron. The antihistamines and decongestants respectively in these drugs include Brompheniramine and Pseudoephedrine (for Bromfed-PD); fexofenadine and pseudoephedrine for Allegra-D; pyrilamine and phenylephedrine for Aldex-D, and; chlorpheniramine and phenylephrine for Ceron.
Relief from Colds: Between Antihistamines and Decongestants
As noted earlier, both drugs are used for the same purposes but produce somewhat dissimilar results and may cause serious health complications, respectively. Consequently, while both provide relief from cold and flu symptoms, it is crucial to speak with a physician to help decide which of the two is suitable based on one’s health needs.
Note that human body may get used to both antihistamines and decongestants, which can result in physical and psychological dependence. However, this condition can be treated. One of the easiest way to recover from allergy medication dependence is to ask for help in one of the addiction rehab clinics.
Page Sources
- De Sutter AI, van Driel ML, Kumar AA, Lesslar O, Skrt A. Oral antihistamine-decongestant-analgesic combinations for the common cold. Cochrane Database Syst Rev. 2012. https://www.ncbi.nlm.nih.gov/pubmed/22336807
- May JR, Dolen WK. Management of Allergic Rhinitis: A Review for the Community Pharmacist. Clin Ther. 2017 Dec;39(12):2410-2419. https://www.clinicalkey.com/#!/content/playContent/1-s2.0-S0149291817310068
