Viral and allergic conjunctivitis somtime time show similar picture, it is physical examination and specific symptoms which differenciates it. But don't self medicate. Consult ophthalmologist and avoid side effects of long term use of certain drugs.

By photo ,only this much can be said . For diagnosis,physical examination is necessary.

Allergic  usually  in both eyes and Viral in only one eye

In allergic conjunctivitis your problem will be mainly itching with mild redness of eyes .it could be seasonal .viral conjunctivitis will have more of ocular discomfort ,mild pain ,redness sometimes lid swellingand discharge if there is additional bacterial component of infection.these are few differences based on your symptoms.But these can be differentiated definitely only by clinical examination by ophthalmologist.

In viral conjunctivitis there will be lot of watering and discharge. But these two can be distinguished only on clinical examination. Please send a pic of your eye.