In some embodiments, the present invention provides methods of treating oxidative stress in a subject by administering a therapeutic composition to the subject. In some embodiments, the therapeutic composition comprises a carbon nanomaterial with anti-oxidant activity. In some embodiments, the anti-oxidant activity of the carbon nanomaterial corresponds to ORAC values between about 200 to about 15,000. In some embodiments, the administered carbon nanomaterials include at least one of single-walled nanotubes, double-walled nanotubes, triple-walled nanotubes, multi-walled nanotubes, ultra-short nanotubes, graphene, graphene nanoribbons, graphite, graphite oxide nanoribbons, carbon black, oxidized carbon black, hydrophilic carbon clusters, and combinations thereof. In some embodiments, the carbon nanomaterial is an ultra-short single-walled nanotube that is functionalized with a plurality of solubilizing groups. In some embodiments, the carbon nanomaterial is a polyethylene glycol functionalized hydrophilic carbon cluster (PEG-HCC). In some embodiments, the administered therapeutic compositions of the present invention may also include an active agent or targeting agent associated with the carbon nanomaterial. Additional embodiments of the present invention pertain to the aforementioned carbon nanomaterial compositions for treating oxidative stress.