Histamine may also have a role in causing coughs, but this is less certain.
Cold treatments recommended in have been properly tested and found to be effective.
Their side effects are known and are acceptable for treating a mild illness like a cold.
Antihistamines like Zyrtec and Claritin are designed to calm the histamine reaction your body has when it’s exposed to an allergen.
When your body encounters something it’s allergic to, it sends out white blood cells and goes into fight mode. This substance causes many of the symptoms of an allergic reaction.
They include the following: A common cold is a two step process (see How Cold Virus Infection Occurs and What Causes Cold Symptoms). The second step is the activation of the inflammatory mediators which directly cause the cold symptoms.
Ideally, it is desirable to treat both parts of the process but currently drugs for treating the virus infection (antivirals) are not commercially available.They both calm your immune system’s reaction to allergens. They also take effect at different times and stay effective for different durations. Antihistamines have a reputation of making you sleepy because the first types crossed into your central nervous system more easily and had a direct effect on your alertness.These factors could determine which of these two drugs is better for you. However, newer antihistamines like Zyrtec and Claritin are less likely to cause this side effect. Most people experience at least 24 hours of relief after a single dose. People who take it may feel relief in as little as one hour.Histamine is a natural substance, one of the important inflammatory mediators produced in certain cells in the body.(20) When introduced into the nose, histamine causes dilatation and leakage of blood vessels.It is hardly surprising, therefore, that these first-generation antihistamines had poor receptor selectivity and significant unwanted side effects.