Decongestants Indications Antihistamines are useful for treating hayfever which is a histamine problem. They have no direct benefit for treating the common cold which is not a histamine problem. On the other hand, they are useful for treating the main symptom of a cold, insomnia.
Antihistamines are good at reducing the itching and sneezing that are associated with hayfever.
They may also help the runny nose if they have drying effects. They do not reduce congestion. Use of these drugs can therefore provide one with a dry, non-itchy but still congested nose. Side effects Their side effects generally include sedation and drying. For that reason, one should not drink when taking these agents nor should one operate heavy machinery.