Allergy

General Oral Medications for All Allergy Symptoms
For all allergy symptoms (red, itchy eyes; itchy skin; nasal congestion; cough), the class of the all-purpose active ingredient in many allergy medications is called antihistamine. This class of drug blocks histamine, which causes the allergy symptoms people experience when they come into contact with the allergen they are allergic to.
Though antihistamines can relieve your allergy symptoms, some may induce drowsiness, which can affect your daily activities after taking the allergy medication, for example, chlorpheniramine and diphenhydramine. However, there are currently two antihistamine ingredients available over-the-counter that do not cause drowsiness, and they are loratadine and fexofenadine. An antihistamine that causes mild drowsiness is certirizine. Note that medications with antihistamines that does induce drowsiness work more effectively than medications with antihistamines that does not cause drowsiness.

In conclusion, antihistamines that do not cause drowsiness should be taken during the daytime, and antihistamines that does cause drowsiness should be taken at nighttime or before sleep.
For nasal congestion (more commonly known as stuffy or runny nose), oral medications containing a decongestant will help to clear this stuffy or runny nose. The common decongestant you will see in over-the-counter oral medications is phenylephrine. A pro about this ingredient is that it does not cause drowsiness, making it suitable to use during the daytime.

For Cough
If you cannot get relief from taking Robitussin DM, you can take it in combination with an antihistamine, oftentimes that combination will resolve the coughing problem. Actually, in many instances, the antihistamine alone can relieve your coughing symptom.

Decongestant Warning for those with Hypertension:
Decongestants can cause hypertension, so for people with hypertension, or high blood pressure, they will need to watch out for this side effect. Its better to avoid these products if possible.