Antihistamines, Decongestants & Cold Remedies


Drugs for stuffy nose, sinus trouble, congestion, and the common cold constitute the largest segment of the over-the-counter market for 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., sinusitis, 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 more comfortable.


Antihistamine exerts their therapeutic effect by blocking histamine (H1) receptors in the nose and throat, the antibody-antigen complex that occurs during allergic reaction releases histamine.

Histamine is an important body chemical that is responsible for congestion, sneezing, running nose that a patient suffers with an allergic attack or an infection. Histamine causes vasodilatation, which causes blood vessels and tissues to become enlarged, swollen and red. It also irritates these tissues directly, causing pain and itching. Antihistamines block the action of histamine at the H1, receptors therefore reducing the allergic symptoms. For the best result, antihistamines should be taken before allergic symptoms get well established.

The most annoying side effect that antihistamines cause 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, do not have this effect. The first few doses cause the greatest sleepiness; subsequent doses are usually less troublesome.

  • Drugs of antihistamines include
  • Diphenhydramine (Benadryl),
  • Ceritirizine (Zyrtec, Cetrizet, Rhizin) chlorpheneramine (Avil)
  • Chlor-Trimetron
  • Loratidine (Loridin, Lormeg, Alaspan)
  • Brompheneramine (Dimetane)
  • Fexofenadine (Allegra)
  • PBZ,
  • Dexchlorpheniramine (Polaramine)
  • Clemastine (Tavist)
  • Teldrin, azelasitne (Astelin), triprolidine (Actidil)

Antihistamines are only effective in treating allergic reactions, which release histamine. They are not effective in treating the common cold.


By stimulating alphareceptors the decongestant act as vasoconstrictors to reduce flow to edematous tissues in the nose, sinuses and pharynx. They decrease the swelling of mucous membranes, alleviate nasal stuffiness, allow secretions to drain, and help to unclog the Eustachian tubes.

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 are commonly prescribed for colds and allergies. On the other hand, decongestants 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, nightmares, and they can elevate blood pressure and pulse rate. A patient who has an irregular heart rhythm (pulse), high blood pressure, heart disease, or glaucoma should not use it. 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
  • Ephedrine
  • Oxymetazoline (Nasivion, Dristan)
  • Phenylephrine (Neo-Synephrine, Nostril)
  • Phenylpropanolamine (Dura-Vent, Propagest, Entex)
  • Pseudoephedrine (Sudafed)
  • Xylometazoline (Otrivin)

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.

The following trade name drugs contain various combination of antihistamines with decongestants are available:

Actifed, Alerid.D, Sine aid, Actifed Plus, Sudafed Plus, Triaminic, 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: Antihistamine (Cetrizine 10 mg) one tablet 2 times daily.

Plus Decongestant (Sudafed, 30mg)-two tablets three times daily and one tablet at bedtime.

Medicine Symptoms Relieved Possible Side Effects
Antihistamines Sneezing
Runny Nose
Stuffy Nose
Itchy Eyes
Dry Mouth & Nose
Decongestants Stuffy Nose
Rapid Heart Beat
Combinations of above All of above Any of above (more or less)

“Cold” remedies:

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 sprays/Drops:

The types of nasal sprays that can be purchased without a prescription of doctor, it may usually contain decongestants for direct application to nasal membranes. They 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 congestion.

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 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 may contain the warning “Do not use this product for more than three days.” It 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.)

Steroid ( fluticasone ) Nose drops are dispensed for our chronic allergic patients in 3 strengths.These do not contain proppellent and preservative chemicals and hence are gentle to the nasal membranes.We rely on these when patient has exposure to high atmospheric pollution and when the airborne allergic substance cannot be avoided.They are our mainstay of defence to avoid recurrent polyps in patients who undergo nose operations. We also recommend using them in the months of nov,dec and jan to avoid nose complications that may lead to surgery.