High gain Erbium Doped Fiber Amplifiers (EDFAs), while revolutionizing optical communications, remain vulnerable to optical damage when unseeded, e.g. due to nonlinear effects that, due to spontaneous Q switching, produce random pulses with high peak power, i.e. giant pulses. Giant pulses can damage either the components within a high gain EDFA or the external components and systems coupled to the EDFA. We explore the conditions under which a reflective, polarization-maintaining (PM), core-pumped high gain EDFA generates giant pulses, provide details on conditions under which normal pulses evolve into giant pulses, and provide results on the transient effects of giant pulses on an amplifier’s fused-fiber couplers, such as pump-signal combining wavelength division multiplexers (WDMs), an effect which we call Fused-coupler Overload Induced Leakage (FOIL). While FOIL’s effect on fused-fiber couplers is temporary, its damage to forward pump lasers in a high gain EDFA can be permanent, e.g. damage to the pump’s front facet.