The NASUWT and the National Education Union have called for pay rises.
Two key teaching unions are considering balloting members over strike action if a significant pay increase is not offered.
The National Education Union (NEU) said a letter will be sent to Education Secretary Nadhim Zahawi on Wednesday saying the union is prepared to ballot its members if a pay rise more in line with inflation is not offered.
However, a ballot will not be called until Mr Zahawi responds to the conclusions of the School Teachers’ Review Body report, which is expected to be released at the end of the school year.
The union said an initial indicative ballot would be taken, followed by a formal ballot if the first result suggests members support strike action.
NASUWT leaders have also called for a 12% pay increase for teachers this year, and said it will ballot members in England, Wales and Scotland for industrial action if its demands are not met.
A pay award for 2022/23 is due in November.
Two in three teachers are questioning whether to change careers due to wages, and the value of teachers’ pay has dropped by 20%, NASUWT said.
Dr Mary Bousted, fellow joint general secretary of the NEU, said: “The case for a better deal for teachers will be set out in full this Wednesday in our letter to the Secretary of State.
“If it should fall on deaf ears, and teachers are offered a pay rise significantly below inflation, then we will proceed to an indicative ballot of our members.
“Teachers have had enough of a government which simply does not value them.
“The combination of unsustainable hours, the work intensity during those hours and ever-falling pay levels are damaging for our schools and the young people we are educating.
“The Government has so far been unwilling to acknowledge and properly remunerate the work that teachers do.
“Teacher pay has fallen by a fifth in real terms since 2010.
“We need a pay deal for all teachers which recognises this reality.”
Dr Patrick Roach, NASUWT general secretary, said: “The country faces an existential emergency for the future of the teaching profession.
“Teachers are suffering, not only from the cost-of-living crisis, which the whole country is grappling with, but 12 years of real terms pay cuts which has left a 20% shortfall in the value of their salaries.
“If the Government and the pay review body reject a positive programme of restorative pay awards for teachers, then we will be asking our members whether they are prepared to take national industrial action in response.
“The Government wrongly assumed teachers would simply stand by as they erode pay and strip our education system to the bone.
“But this weekend, thousands of teachers, from every corner of the UK, joined together to demonstrate our strength, unity and determination to stand up and to fight back.
“Our message is clear and has now been delivered directly to the Government on their doorstep.
“We will not allow cuts to our members’ pay and attacks on their pensions.
“If a pay rise is not awarded, it will be won by our members in workplaces through industrial action.”
The NASUWT was a prominent group in a large rally on Saturday, organised by the Trades Union Congress (TUC), which saw thousands of protesters march through central London to demand better pay and working conditions.