Almost nine in 10 doctors (87%) said they increasingly feared facing legal action and more than four-fifths (84%) said this had led them to order additional tests or make more referrals to specialists, according to research by the Medical Protection Society (MPS).
More than two-fifths of GPs surveyed (41%) admitted to prescribing medication when not clinically necessary due to their concerns.
The MPS, which provides professional protection to more than 300,000 medics around the world, criticised the "cultural acceptability" to sue when limited inconvenience and no loss of income has occurred.
The organisation called for a minimum threshold for financial compensation to reduce the number of claims for minor injuries and reduce pressure on doctors.
One anonymous GP said the number of claims were leading to "defensive practice" and "over-investigating", which was racking up costs for the NHS.
They said: "The stress anxiety and sleepless nights this causes us is terrible and disproportionate, time that could be spent caring for patients and reviewing process and protocol to improve future care is spent worrying about this."
Another added: "I worry about claims which are inappropriate, patients threatening complaints if not given the tests they want, and more professionals managing cases driven by fear of litigation as opposed to what is in the best interests of the patient."
In 2016/17, 817 NHS clinical negligence claims resulted in damages under £3,000 being paid out, compared to 646 the previous year.
Dr Pallavi Bradshaw, senior medicolegal adviser at MPS, said: "Unnecessary tests or investigations are not in the best interests of patients and may use up limited NHS resources.
"Doctors should be able to exercise their clinical skills and judgment without the fear of claims affecting their decision-making.
"A full-time GP can now expect to receive two clinical negligence claims over their career; the environment is challenging and the temptation to over-prescribe or over-investigate is understandable."
She added: "While those who suffer serious and long-term harm due to clinical negligence should be reasonably compensated, it is right that we question the extent to which those who sustain minor injuries can recover compensation.
"We are calling on government to consider a minimum threshold for these types of claims and we stand ready to work together on what we recognise is a difficult debate."
More than 1,300 doctors in the United Kingdom took part in the MPS survey earlier this year.