In this study, we examined the influence of cold and hot environments on methamphetamine (METH) neurotoxicity in both drug-naive rats and animals previously exposed to different types of nanoparticles (NPs). Since METH induces oxidative stress, we also examined how a potential chain-braking antioxidant H-290/51 (Astra-Zeneca Mölndal, Sweden) affects METH-induced neurotoxicity. Exposure of drug-naive rats to METH (9 mg/kg, s.c.) at 4°, 21° or 34°C for 3 hrs resulted in breakdown of the blood-brain barrier (BBB), brain edema and neuronal injuries, which all differed in their extent depending upon ambient temperatures. The changes were moderate at 21°C, 120–180% larger at 34°C, and almost absent at 4°C. In rats chronically treated with NPs (SiO2, Cu or Ag; 50–60 nm, 50 mg/kg, i.p. for 7 days), METH-induced brain alterations showed a 2- to 4-fold increase in brain pathologies after METH at 21°C; 4-to 6-fold increase at 34°C and 3- to 4-fold increase at 4°C. SiO2 exposure showed the most pronounced METH-induced brain pathology at all temperature ranges followed by Ag and Cu NPs. Pretreatment with a potent antioxidant compound H-290/51 (50 mg/kg, p.o. 30 min before METH) significantly reduced brain pathology in naive animals exposed to METH at 21°C and 34°C. In NPs-treated animals, however, attenuation of METH-induced brain pathology occurred only after repeated exposure of H-290/51 (−30 min, 0 min and +30 min). These observations are the first to show that NPs aggravate METH-induced brain pathology in both cold and hot environments and demonstrate that timely intervention with antioxidant H-290/51 could have neuroprotective effects.