Conjunctivitis does not get better quickly with injections because conjunctivitis is mainly a localized lesion, confined to the level of the conjunctiva, and local medication can provide relief. Even if systemic injections or oral medications are administered, the effect may not be advanced. For example, infectious conjunctivitis, i.e. bacterial or viral infection, requires antibacterial and antiviral treatment, which may not be as effective as injections or oral medications. In the case of non-infectious conjunctivitis, such as allergy or immune response related conjunctivitis, topical medication is usually sufficient to relieve the symptoms for 1-2 weeks, and the effect of injections is not too strong and does not shorten the course of improvement. If the allergy or immune reaction is combined with other organs, then the injection may have some effect.