The pair became trapped for an hour on Tanners Lane beach when the mother went to help her youngster who was submerged in the mud up to her knees.
The incident happened about 30 metres from the shoreline on Sunday afternoon and Lymington Coastguard, assisted by Hill Head Coastguard and Hampshire Fire and Rescue Servicer, were called to rescue them.
A father and son were also at the scene although, thankfully, they didn’t become trapped in the mud.
Colin Tabor, station officer at Lymington Coastguard, said: "This was a challenging one because of the location and also because we were faced with deteriorating weather conditions and a flood tide. There was also some concern about the cold and how it might affect the casualties. We had all just re-qualified two weeks previously in mud rescue and these kind of incidents show the value of such training."
The pair were transferred to Southampton General Hospital for medical care and the mother was treated for the effects of the cold while the eleven-year-old was treated for a leg injury.
