Histamine is one of the chemicals released when antibodies overreact to allergens. It is the cause of many symptoms of allergic rhinitis. Antihistamine drugs can help relieve:
- Itching, sneezing, and runny nose (unless combined with a decongestant, antihistamines do not work well for relieving nasal congestion).
- Other allergy symptoms unrelated to rhinitis, including hives and some rashes
If possible, take an antihistamine before an anticipated allergy attack.
Many antihistamines are available. They include short-acting and long-acting forms, and come in oral pill and nasal spray forms.
Antihistamines are generally categorized as first and second generation. First-generation antihistamines, which include diphenhydramine (Benadryl, generic) and clemastine (Tavist, generic) cause more side effects (such as drowsiness) than most newer second-generation antihistamines. For this reason, second-generation antihistamines are generally preferred and recommended over first-generation antihistamines.
Here are some notes of caution when taking any antihistamine:
- Antihistamines may thicken mucus secretions and can worsen bacterial rhinitis or sinusitis.
- Antihistamines can lose their effectiveness over time and you may need to try a different one.
Second-generation antihistamines are sometimes referred to collectively as nonsedating antihistamines. However, cetirizine (Zyrtec, generic) and the nasal spray antihistamines (Astelin, Patanase) may cause drowsiness when taken at recommended doses. Loratadine (Claritin, generic) and desloratadine (Clarinex) can cause drowsiness when taken at doses exceeding the recommended dose.
Brand Names. Second-generation antihistamines in pill form include:
- Loratadine (Claritin, generic). Loratadine is available over the counter and is approved for children age 2 and older. Loratadine-D (Claritin-D) combines the antihistamine with the decongestant pseudoephedrine. Desloratadine (Clarinex) is similar to Claritin, but is stronger and longer-lasting. It is available only by prescription.
- Cetirizine (Zyrtec, generic). Cetirizine is approved for both indoor and outdoor allergies. It is the only antihistamine to date approved for infants as young as 6 months. It is available over the counter. Cetirizine-D (Zyrtec-D) is a pill that combines the antihistamine with the decongestant pseudoephedrine.
- Fexofenadine (Allegra, generic) is also available over the counter.
- Levocetirizine (Xyzal) is a prescription medication approved to treat seasonal allergic rhinitis in patients age 2 and older. It is available in both pill and liquid form.
- Acrivastine and pseudoephedrine (Semprex-D) is a pill that combines an antihistamine and decongestant.
Second-generation antihistamines in nasal form are as good as, or better than the oral forms for treating seasonal allergic rhinitis. However, they can cause drowsiness, and they are not as effective for allergic rhinitis as nasal corticosteroids. Nasal spray antihistamines are available by prescription and include:
- Azelastine (Astelin, Astepro, Dymista)
- Olopatadine (Patanase)
In 2013, the FDA approved a liquid form of antihistamine for treatment of seasonal and perennial allergic rhinitis. Carbinoxamine maleate (Karbinal ER) is approved for patients age 2 and older.
Side Effects and Precautions.
- Common side effects include headache, dry mouth, and dry nose. (These are often only temporary and go away during treatment.)
- Drowsiness may occur. The nasal spray forms of second-generation antihistamines cause more drowsiness than the pill forms.
- Extended-release forms of loratadine and cetirizine have additional ingredients that can cause other symptoms, including nervousness, restlessness, and insomnia.
Corticosteroids help reduce the inflammatory response associated with allergic reactions. Nasal-spray corticosteroids (commonly called steroids) are considered the most effective drugs for controlling the symptoms of moderate-to-severe allergic rhinitis. They are often used alone or in combination with second-generation oral antihistamines.
The benefits of nasal spray steroids include:
- Reducing inflammation and mucus production
- Improving night sleep and daytime alertness in patients with chronic allergic rhinitis
- Treating polyps in the nasal passages
Nasal-Spray Brands. Corticosteroids available in nasal spray form include:
- Triamcinolone (Nasacort) is the only nasal steroid available without a prescription. Approved for patients age 2 and older.
- Mometasone furoate (Nasonex). Approved for patients age 2 and older.
- Fluticasone (Flonase, generic). Approved for patients age 2 and older.
- Fluticasone and azelastine (Dymista). Approved for patients age 12 and older.
- Beclomethasone (Beconase, Vancenase, generic). Approved for patients age 6 and older.
- Flunisolide (Nasarel, generic). Approved for patients age 6 and older.
- Budesonide (Rhinocort, generic). Approved for patients age 6 and older.
- Ciclesonide (Alvesco, Omnaris). Approved for patients age 12 and older
Side Effects. Corticosteroids are powerful anti-inflammatory drugs. Although oral steroids can have many side effects, the nasal-spray form affects only local areas and has less risk for widespread side effects, unless the drug is used excessively. Side effects of nasal steroids may include:
- Dryness, burning, stinging in the nasal passage
- Headaches and nosebleed (uncommon, but should be reported to your doctor immediately)
Possible Long-Term Complications. All corticosteroids suppress stress hormones. This effect can produce some serious long-term complications in people who take oral steroids. Researchers have found far fewer concerns with nasal administration or inhaled forms, but there may still be certain problems, including:
- Effect on growth. The major concern for children is whether nasal steroids, like other forms of steroids, will adversely affect growth. Research indicates that most children who only take the recommended dosages of nasal sprays, and do not also take inhaled corticosteroids for asthma, will not have any problems.
- Effect on eyes. Glaucoma is a known side effect of oral steroids. Studies to date have not shown that nasal steroids increase the risk for glaucoma. Still, patients should have periodic eye exams.
- Use during pregnancy. Steroids are most likely safe during pregnancy, but if you are pregnant talk to your doctor before taking them.
- Nasal passage injury. Steroid sprays may injure the nasal septum (the bony area that separates the nasal passage) if the spray is directed onto it. This complication is very rare.
- Lowered resistance to infection. People with any infectious disease or injury in the nose should not take these drugs until the disease or wound has been treated and cured.
Cromolyn is both an anti-inflammatory drug and a specific blocker for allergens. The standard cromolyn nasal spray (NasalCrom, generic) is not as effective as steroid nasal sprays, but it does work well for many people with mild allergies. It is one of the preferred first-line therapies for pregnant women with mild allergic rhinitis. It may take up to 3 weeks to experience the full benefit.
Side Effects. Cromolyn has no major side effects, but minor ones include nasal congestion, coughing, sneezing, wheezing, nausea, nosebleeds, and dry throat. The spray can cause burning or irritation.
Leukotriene antagonists are oral drugs that block leukotrienes, powerful immune system factors that cause airway constriction and mucus production in allergy-related asthma. They appear to work as well as antihistamines for treatment of allergic rhinitis, but are not as effective as nasal corticosteroids.
Leukotriene antagonists include zafirlukast (Accolate, generic) and montelukast (Singulair, generic). These drugs are mainly used to treat asthma. Montelukast is also approved to treat seasonal allergies and indoor allergies.
The FDA warns that these drugs have been associated with behavior and mood changes, including agitation, aggression, anxiousness, dream abnormalities, hallucinations, depression, insomnia, irritability, restlessness, tremor, and suicidal thinking and behavior. Patients who take a leukotriene antagonist drug such as montelukast should be monitored for signs of behavioral and mood changes. Doctors should consider discontinuing the drug if patients exhibit any of these symptoms.
Decongestants work by shrinking blood vessels in the nose. Many over-the-counter decongestants are available, which can be either taken by mouth or applied to the nose.
Nasal Decongestants. Nasal-delivery decongestants are applied directly into the nasal passages with a spray, gel, drops, or vapors. Nasal decongestants come in long-acting or short-acting forms. The effects of short-acting decongestants last about 4 hours. Long-acting decongestants last 6 to 12 hours. The active ingredients in nasal decongestants include oxymetazoline, xylometazoline, and phenylephrine. Nasal forms work faster than oral decongestants and may not cause as much drowsiness. However, they can cause dependency and rebound congestion.
The major problem with nasal-delivery decongestants, particularly long-acting forms, is the cycle of dependency and rebound effects. The 12-hour brands pose a particular risk for this effect.
- With prolonged use (more than 3 to 5 days), nasal decongestants lose effectiveness and can cause swelling in the nasal passages.
- The patient then increases the frequency of the dose. As the congestion worsens, the patient may respond with even more frequent doses.
- This causes dependency and increased nasal congestion.
The following precautions are important for people taking nasal decongestants:
- When using a nasal spray, spray each nostril once. Wait a minute to allow absorption into the mucosal tissues, and then spray again.
- Do not share droppers and inhalers with other people.
- Discard sprayers, inhalers, or other decongestant delivery devices when the medication is no longer needed. Over time, these devices can become reservoirs for bacteria.
- Discard the medicine if it becomes cloudy or unclear.
- DO NOT USE NASAL DECONGESTANTS FOR LONGER THAN 3 DAYS.
Oral Decongestants. Oral decongestants also come in many brands, which have similar ingredients. The most common active ingredients are pseudoephedrine (Sudafed, other brands, generic) and phenylephrine, sometimes in combination with an antihistamine. Oral decongestants can cause side effects such as insomnia, irritability, nervousness, and heart palpitations. Taking pseudoephedrine in the morning, as opposed to later in the day or before bedtime, can help patients avoid these side effects.
Individuals at Risk for Complications from Decongestants. People who may be at higher risk for complications are those with certain medical conditions, including disorders that make blood vessels highly susceptible to contraction. Such conditions include:
- Heart disease
- High blood pressure
- Thyroid disease
- Prostate problems that cause urinary difficulties
- Raynaud phenomenon
- High sensitivity to cold
- Chronic obstructive pulmonary disorder (COPD). People with emphysema or chronic bronchitis should avoid high-potency, short-acting nasal decongestants.
No one with these conditions should use oral or nasal decongestants without a doctor's guidance. Other people who should not use decongestants without first consulting a doctor include:
- Pregnant women
- Children; children metabolize decongestants differently than adults. Decongestants should not be used at all in infants and children under age 4, and some doctors recommend not giving them to children under age 14. Children are at particular risk for central nervous system side effects, including convulsions, rapid heart rates, loss of consciousness, and death.
Decongestants can cause dangerous interactions when combined with certain types of medications, such as the antidepressant MAO inhibitors. They can also cause serious problems when combined with methamphetamines or diet pills. Be sure to tell your doctor about any drug or herbal remedy you are taking. Caffeine can also increase the stimulant side effects of pseudoephedrine.
Ipratropium bromide (Atrovent, generic) is a prescription nasal spray that can help relieve runny nose. It works best when given in combination with a nasal corticosteroid. Side effects include nasal dryness, nosebleeds, and sore throat. It should not be used by people who have glaucoma or men who have an enlarged prostate gland.