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We present an analysis of long-term photometric variability for nearby reddwarfs at optical wavelengths. The sample consists of 264 M dwarfs south of DEC= +30 with V-K = 3.96-9.16 and Mv~10-20 (spectral types M2V-M8V), most of whichare within 25 pc. The stars have been observed in the VRI filters for ~4-14years at the CTIO/SMARTS 0.9m telescope. Of the 238 red dwarfs within 25 pc, wefind that only ~8% are photometrically variable by at least 20 mmag (~2%) inthe VRI bands. We find that high variability at optical wavelengths over thelong-term can be used to identify young stars. Overall, however, the fluxes ofmost red dwarfs at optical wavelengths are steady to a few percent over thelong term. The low overall rate of photometric variability for red dwarfs isconsistent with results found in previous work on similar stars on shortertimescales, with the body of work indicating that most red dwarfs are onlymildly variable. We highlight 17 stars that show long-term changes inbrightness, sometimes because of flaring activity or spots, and sometimesbecause of stellar cycles similar to our Sun's solar cycle. Remarkably, twotargets show brightnesses that monotonically increase (G 169-029) or decrease(WT 460AB) by several percent over a decade. We also provide long-termvariability measurements for seven M dwarfs within 25 pc that host exoplanets,none of which vary by more than 20 mmag. Both as a population, and for thespecific red dwarfs with exoplanets observed here, photometric variability istherefore often not a concern for planetary environments, at least at theoptical wavelengths where they emit much of their light.

The Solar Neighborhood XXXVI: The Long-Term Photometric Variability of Nearby Red Dwarfs in the VRI Optical Bands