Decongestants and Antihistamines

What are decongestants and antihistamines?

Decongestants relieve a stuffy nose. Antihistamines help dry up a runny nose. These medicines are often confused with each other because they are both used to help runny, stuffy noses. However, they are different and do not act the same way on your body.

Many nonprescription cold and allergy products contain several types of medicines. They may treat many symptoms. It can be confusing trying to figure out which medicine will help you. Ask your pharmacist or healthcare provider if you are not sure which medicine is best for your symptoms.

How do they work?

Decongestants narrow the blood vessels in the nose. This reduces swelling and makes it easier for you to breathe. It also may reduce the amount of mucus made by your nose. You can buy some decongestants without a prescription. The most common types, with examples of trade names in parentheses, are:

• pseudoephedrine (Sudafed)
• phenylephrine (Neo-Synephrine).
• oxymetazoline (Afrin).

Antihistamines block the effect of histamine. Histamine is a chemical your body makes when you have an allergic reaction. It causes redness and swelling. Antihistamines help decrease congestion, watery eyes, sneezing, and runny nose. Common antihistamine medicines are:

• diphenhydramine (Benadryl)
• chlorpheniramine (Chlor-Trimeton)
• cetirizine (Zyrtec)
• fexofenadine (Allegra)
• loratadine (Claritin)
• desloratadine (Clarinex).
• azelastine (Astelin).

When are they used?

Decongestants are often used to treat:

• colds or hay fever
• ear or sinus infections.

Antihistamines are most often used to treat symptoms of allergies. These include:

• sneezing and runny nose from hay fever
• itching, swelling, and redness from hives or other allergic rashes.

Antihistamines should be used with great caution in older adults. They should be used only if recommended by a healthcare provider.

What should I watch out for?

Decongestants

Decongestants can increase your heart rate and your blood pressure. Because of this effect, you should not take a decongestant without first checking with your healthcare provider if you have:

• heart disease
• high blood pressure
• glaucoma
• thyroid disease
• trouble urinating or an enlarged prostate
• diabetes.

Decongestant nose sprays or drops should not be used for more than 2 or 3 days in a row. After 3 days they may make your symptoms worse by causing more congestion.

Antihistamines

There are different types of antihistamines. In older adults, some antihistamines, such as diphenhydramine (Benadryl) and chlorpheniramine (Chlor-Trimeton), are more likely to cause side effects. Some of the possible side effects are drowsiness, confusion, dizziness, dry mouth and eyes, constipation, trouble urinating, and worsening of glaucoma. Other antihistamines, such as azelastine (Astelin), cetirizine (Zyrtec), fexofenadine (Allegra), loratadine (Claritin), and desloratadine (Clarinex), are safer but may cause confusion. Ask your healthcare provider to recommend an antihistamine.

If you have any of the following medical problems, check with your provider before taking antihistamines:

• glaucoma
• hyperthyroidism (overactive thyroid gland)
• high blood pressure
• enlarged prostate
• heart disease
• ulcers
• stomach or intestinal blockage
• liver disease
• kidney disease
• bladder obstruction
• diabetes.

Taking antihistamines with other medicines, such as antidepressants or sedatives, may cause problems. Read the labels carefully. Ask your provider or pharmacist if you have any questions.