The rhinovirus is contagious one to four days before the patient notices the
symptoms of the cold. This is referred to as the incubation period. During this
time, the rhinovirus can be transmitted by touching contaminated surfaces and
from contact with droplets from an infected patient who sneezes and coughs.
After the incubation period, the patient experiences a watery nasal discharge
called rhinorrhea, nasal congestion, cough, and an increasing amount of
mucosal secretions.
Many patients try home remedies to battle the rhinovirus, however these
don’t affect the virus. Instead, they may help ease the symptoms of the cold.
Home remedies include rest, vitamin C, mega doses of other vitamins, and, of
course, chicken soup. Vitamin C and mega doses of other vitamins have not been
proven effective against the common cold.
When home remedies fail, patients turn to both prescription and over-the-
counter medication. Cold medications fall into the following drug groups.
Charts throughout these pages provide information about specific drugs in
each group.
Antihistamines (H 1 blocker)
Many cold symptoms are caused by the body’s overproduction of histamines.
Histamines are potent vasodilators that react to a foreign substance in the body
such as the rhinovirus. They cause redness, itching, and swelling. They are part
of the body’s defense mechanism. Antihistamines are drugs that compete for the
same receptor sites as histamines. Once they latch onto the site, there is no room
for the histamine. Therefore, the reaction caused by the histamine doesn’t occur.
It is this reaction that produces many cold symptoms.
There are two types of histamine receptors: H 1 and H 2. H 2 receptors cause an
increase in gastric secretions and are not involved in this response. The differ-
ences are illustrated in the charts. (See Antihistamine (H 1 blocker) chart and
Antihistamine Use to Treat Allergic Rhinitis chart.)
Decongestants (sympathomimetic amines)
Patients have a runny nose when they get a cold. This is referred to as nasal con-
gestion and is caused when the nasal mucous membranes swell in response to
the rhinovirus. A decongestant is a drug that stimulates the alpha-adrenergic
receptors to tell the brain to constrict the capillaries within the nasal mucosa. The
result is that the nasal mucous membranes shrink, reducing the amount of fluid
that is secreted from the nose. That is, a decongestant stops a runny nose.
Decongestants are available in nasal spray, drops, tablets, capsules, or in liq-
uid form. Although decongestants address the congestion, frequent use of decon-
CHAPTER 14 Respiratory Diseases^257