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.
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
A common side effect of antihistamines is drowsiness. Some types
are less likely than others to make you drowsy. This may not be a
problem if a dose at bedtime is all you need. Or you might try the
medicine for several days despite the drowsiness. Often the
drowsiness goes away after you have taken the drug for 3 to 5
days.
Some "nonsedating" antihistamines are available. These
antihistamine medicines usually do not cause drowsiness. They work
well for most people, but they tend to cost more than other
antihistamines.
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.
If you are pregnant, talk with your healthcare provider before
taking these medicines.
This content is reviewed periodically and is subject to
change as new health information becomes available. The
information is intended to inform and educate and is not a
replacement for medical evaluation, advice, diagnosis or
treatment by a healthcare professional.
© 2009 RelayHealth and/or its affiliates. All Rights Reserved.