Addiction services in England could struggle to cope with "soaring" numbers of people misusing alcohol, the Royal College of Psychiatrists is warning.
Many adults are drinking more since the coronavirus pandemic began, data shows.
The college estimates that in June, more than 8.4m people in England were drinking at higher-risk levels, up from 4.8m in February.
It says deep cuts made to addiction services could mean patients will miss out on life-saving care.
The rise in risky drinking comes at a time when more people addicted to opiates are seeking help from addiction services, says the college, referring to National Drug Treatment Monitoring System statistics showing 3,459 new adult cases in April - up 20% from 2,947 in the same month the previous year.
Guidelines advise people drink no more than 14 units of alcohol (equivalent to six large glasses of wine or six pints of beer) a week, spreading consumption over three days or more.
Drinking too much can damage your liver and increases the risk of other health conditions such as heart disease and stroke.
People with alcohol use disorder are more likely to develop serious complications if they catch Covid-19.
The college is asking the government to invest millions more in addiction services.
Prof Julia Sinclair, chair of the college's addictions faculty, said: "Covid-19 has shown just how stretched, under-resourced and ill-equipped addiction services are to treat the growing numbers of vulnerable people living with this complex illness.
"There are now only five NHS inpatient units in the country, and no resource anywhere in my region to admit people who are alcohol dependent with co-existing mental illness.
"Drug-related deaths and alcohol-related hospital admissions were already at all-time highs before Covid-19. I fear that unless the government acts quickly we will see these numbers rise exponentially."
Laura Bunt from the drug, alcohol and mental health charity We Are With You said: "Social isolation and a lack of a human connection is a big factor behind why some people turn to alcohol as a coping mechanism, so clearly the pandemic continues to be really tough for many people.
"When you consider that the UK had some of the highest levels of alcohol-related harms in Europe even before the lockdown in March, the need for government action now is clear."
A Department of Health and Social Care spokesperson said: "We have increased their funding this year, providing over £3.2 billion to spend on public health services like addiction.
"We support evidence-based approaches to reduce the health-related harms of drug misuse and, as part of our NHS Long Term Plan, alcohol care teams will be introduced in hospitals where alcohol-related admissions are high, intervening in 50,000 cases over five years to reduce harm."
If you are concerned about addiction, BBC Action Line has help and support.