Yes, if your 6-month-old baby has conjunctivitis in their left eye due to a cold, you can purchase something at the pharmacy to help. If there are yellowish/greenish discharge and the eye is sticking together in the morning, it is likely related to the cold and should resolve on its own. You can clean the eye with a clean, damp cloth and avoid sharing it to prevent spreading the infection. If there is no improvement after 7 days or if it worsens, it's important to consult a doctor for proper treatment.