Molecular Communication (MC) is a bio-inspired paradigm where information is exchanged by the release, the propagation and the reception of molecules. The objective of this paper is to analyze the effects of interference in the most general type of MC system, i.e., the diffusion of molecules in a fluidic medium. The study of the InterSymbol Interference (ISI) and Co-Channel Interference (CCI) is conducted through the analysis of the propagation of signals in a diffusion-based channel. An in-depth analysis of the attenuation and the dispersion of signals due to molecule diffusion allows to derive simple closed-form formulas for both ISI and CCI. In this paper, two different modulation schemes, namely, the baseband modulation and the diffusion wave modulation are considered for the release of molecules in the diffusion-based MC and are compared in terms of interference. It is determined that the diffusion wave modulation scheme shows lower interference values than the baseband modulation scheme. Moreover, it is revealed that the higher is the frequency of the modulating diffusion wave, the lower are the effects of the ISI and the CCI on the communication channel. The obtained analytical results are compared and validated by numerical simulation results.