Doctor, Should I take Antihistamines?
Insight into decongestants and cold remedies
Drugs for stuffy nose, sinus trouble,
congestion, and the common cold constitute the largest segment of the
over-the-counter market for America's pharmaceutical industry. When used wisely,
they provide welcome relief for at least some of the discomforts that affect
almost everyone occasionally and that affect many people chronically. Drugs in
these categories are useful for relief of symptoms from allergies, upper
respiratory infections (i.e., sinusitus, colds, flu), and vasomotor rhinitis (a
chronic stuffy nose caused by such unrelated conditions as emotional stress,
thyroid disease, pregnancy, and others). These drugs do not cure the allergies,
infections, etc.; they only relieve the symptoms, thereby making the patient
Antihistamines, Decongestants, and "Cold"
Histamine is an important body chemical that is responsible for the
congestion, sneezing, and runny nose that a patient suffers with an allergic
attack or an infection. Antihistamine drugs block the action of histamine,
therefore reducing the allergy symptoms. For the best result, antihistamines
should be taken before allergic symptoms get well established.
The most annoying side effect that antihistamines produce is drowsiness.
Though desirable at bedtime, it is a nuisance to many people who need to use
antihistamines in the daytime. To some people, it is even hazardous. These drugs
are not recommended for daytime use for people who may be driving an automobile
or operating equipment that could be dangerous. Newer non-sedating
antihistamines, available by prescription only, do not have this effect. The
first few doses cause the most sleepiness; subsequent doses are usually less
Typical antihistamines include Benadryl,®* Chlor-Trimetron,®* Claritin,®
Dimetane,®* Allegra,® PBZ,®* Polaramine,® Tavist,®* Teldrin,® Zyrtec,®
Congestion in the nose, sinuses, and chest is due to swollen, expanded, or
dilated blood vessels in the membranes of the nose and air passages. These
membranes have an abundant supply of blood vessels with a great capacity for
expansion (swelling and congestion). Histamine stimulates these blood vessels to
expand as described previously.
Decongestants, on the other hand, cause constriction or tightening of the
blood vessels in those membranes, which then forces much of the blood out of the
membranes so that they shrink, and the air passages open up again.
Decongestants are chemically related to adrenalin, the natural decongestant,
which is also a type of stimulant. Therefore, the side effect of decongestants
is a jittery or nervous feeling. They can cause difficulty in going to sleep,
and they can elevate blood pressure and pulse rate. Decongestants should not be
used by a patient who has an irregular heart rhythm (pulse), high blood
pressure, heart disease, or glaucoma. Some patients taking decongestants
experience difficulty with urination. Furthermore, decongestants are often used
as ingredients in diet pills. To avoid excessively stimulating effects, patients
taking diet pills should not take decongestants.
Typical decongestants are phenylephrine (Neo-Synephrine®*),
phenylpropanolamine (Dura-Vent,® Entex,®), and pseudoephedrine (Novafed,®*
* May be available over-the-counter without a prescription. Read labels
carefully, and use only as directed.Combination remedies
Theoretically, if the side effects could be properly balanced, the sleepiness
sometimes caused by antihistamines could be cancelled by the stimulation of
decongestants. Numerous combinations of antihistamines with decongestants are
available: Actifed,®* Allegra-D,® Chlor-Trimetron D,®* Claritin D,® Contac,®*
Co-Pyronil 2,®* Deconamine,® Demazin,®* Dimetapp,®* Drixoral,®* Isoclor,®*
Nolamine,® Novafed A,® Ornade,® Sudafed Plus,® Tavist D,®* Triaminic,®* and
Trinalin,® to name just a few.
A patient may find one preparation quite helpful for several months or years
but may need to switch to another one when the first loses its effectiveness.
Since no one reacts exactly the same as another to the side effects of these
drugs, a patient may wish to try his own ideas on adjusting the dosages. One
might take the antihistamine only at night and take the decongestant alone in
the daytime. Or take them together, increasing the dosage of antihistamine at
night (while decreasing the decongestant dose) and then doing the opposite for
daytime use.For example:
4mg)-one tablet three times daily and two tablets at bedtime.
Decongestant (Sudafed,®* 30mg)-two tablets three
times daily and one tablet at bedtime.
||Possible Side Effects|
Dry Mouth &
|Combinations of above
||All of above
||Any of above (more or
Decongestants and/or antihistamines are the principal ingredients in "cold"
remedies, but drying agents, aspirin (or aspirin substitutes) and cough
suppressants may also be added. The patient should choose the remedy with
ingredients best suited to combat his own symptoms. If the label does not
clearly state the ingredients and their functions, the consumer should ask the
pharmacist to explain them.Nose
The types of nose sprays that can be purchased without a prescription usually
contain decongestants for direct application to nasal membranes. They can give
prompt relief from congestion by constricting blood vessels. However, direct
application creates a stronger stimulation than decongestants taken by mouth. It
also impairs the circulation in the nose, which after a few hours, stimulates
the vessels to expand to improve the blood flow again. This results in a
"bounce-back" effect. The congestion recurs. If the patient uses the spray
again, it starts the cycle again. Spray-decongestion-rebound-and more
In infants, this rebound rhinitis can develop in two days, whereas in adults,
it often takes several more days to become established. An infant taken off the
drops for 12 to 24 hours is cured, but well-established cases in adults often
require more than a simple "cold turkey" withdrawal. They need decongestants by
mouth, sometimes corticosteroids, and possibly (in patients who continuously
have used the sprays for months and years) a surgical procedure to the inside of
the nose. For this reason, the labels on these types of nose sprays contain the
warning "Do not use this product for more than three days." Nose sprays
should be reserved for emergency and short term use.
(The above description and advice does not apply to the type of prescription
anti-allergy nose sprays that may be ordered by your physician.)
© 2004 AAO-HNS/AAO-HNSF
Please read our disclaimer. Any information provided on this Web site should not be considered medical advice or a substitute for a consultation with Dr. Hector N. Hernandez or other healthcare professional. If you have a medical problem, contact us for diagnosis and treatment.