A recently developed formula [R. Bukowski and B. Jeziorski, Phys. Rev.
A46 (1992) 54371. has been applied to estimate the soft-photon Lamb s
hift contribution to the energies of the muonic molecules ppmu, ddmu,
ttmu, pdmu, ptmu and dtmu. The corresponding corrections to the dissoc
iation energies for the excited P states of ddmu and dtmu have been fo
und to be almost identical and equal to 0.048 meV. The magnitude of th
is stabilizing effect is too small to affect seriously the formation r
ates predictions.