Antihistamines for a cold may help relieve symptoms of sneezing and a runny nose. The benefits of antihistamines for a cold is limited, however, as the medication does not cure the cold. Antihistamines do not treat all cold symptoms and may have more side effects than benefits. Some antihistamines, known as second-generation antihistamines, do not help with colds at all.
The primary benefit of taking antihistamines for a cold is that the medication can help calm a runny nose and may stop sneezing. When a person has a cold, the body releases histamine in the nose and sinuses. Histamine makes the nasal passages swell and causes itchiness in the nose. It also changes the consistency of the mucus produced by the nose. The mucus is thin and clear and flows out of the nostrils.
When a person takes an antihistamine for a cold, the medicine works against the histamine. It prevents the sinuses and nasal passages from interacting with histamine, reducing the symptoms. Since the nasal passages are not irritated, a person doesn't feel itchiness or a need to sneeze.
There are only a few types of antihistamines for a cold. Most antihistamines are designed to treat allergies, not viral infections such as the common cold. Not everyone who takes an antihistamine on its own for a cold will see any benefit. Most of the time, antihistamines are packaged with decongestants and pain relievers.
First-generation antihistamines such as brompheniramine and chlorpheniramine are usually effective at treating the symptoms of a cold. Most doctors and medical professionals do not recommend taking second-generation antihistamines for a cold, as they are usually ineffective. Second-generation antihistamines include loratadine, which is found in a lot of allergy medications.
For some people, the side effects of antihistamines for a cold outweigh the benefits. A very common side effect of first-generation antihistamines is drowsiness. Feeling drowsy or sleepy may be ideal at bedtime, but can be dangerous if the patient takes the medicine in the daytime and needs to function. Another common side effect from antihistamines is dryness in the mouth and eyes, which is unpleasant but not particularly dangerous.
Older adults are at greater risk for side effects than healthy, young, or middle-aged adults. With antihistamines, there is a risk of very serious side effects, such as chest tightness and extreme tiredness. If a patient takes multiple medications that contain antihistamines, she risks overdosing. Signs of an overdose include flushing, fainting, and feelings of clumsiness.