A bought curry with all the extras could include almost three-and-a-half times the maximum recommended daily intake of salt, according to a study.
The nation's favourite dish accompanied by rice, naan, sag aloo, poppadom and chutney can contain a "dangerous" 20.5g of salt, Consensus Action on Salt and Health (Cash) said.
The recommended daily maximum is 6g.
A survey of 784 products sold in supermarkets, independent shops and takeaway restaurants revealed "very high" levels of salt hidden in Indian and South Asian takeaways, ready meals, cooking sauces, chutneys, pickles and side dishes.
Iceland's frozen 450g Chicken Tikka Balti contained 7.2g of salt, the equivalent of just over a teaspoon, without any rice, side dishes or chutney.
However salt levels in ready meals varied significantly, with the Sainsbury's Be Good To Yourself Chicken Korma with Pilau Rice containing just 0.91g, almost five times less than a Lidl frozen Kan Pur Garden Chicken Korma with Pilau Rice with 4.5g.
Cash found the salt content of takeaway curries bought in London's "curry street" Brick Lane ranged from 1.37g in a vegetable korma to 6.81g in a chicken tikka masala.
Salt in cooking sauces ranged from 0.5g in a Co-operative Healthy Living Rogan Josh Cook In Sauce and Weightwatchers Korma to 2.49g in a Waitrose Half Fat Jalfrezi Cooking Sauce.
More than half of the pickles and chutneys tested were saltier than Atlantic seawater weight for weight, Cash said.
A 30g spoonful of Priya's Lime Pickle had more than seven times the salt concentration of the sea.
A Marks & Spencer Garlic and Coriander Naan contained 3.2g of salt, more than half the daily maximum. Pataks Plain Mini Pappadums contained 1.1g of salt per portion, more than two packets of crisps.
Cash said a lack of clear labelling combined with spicy ingredients masking the salty flavour made it difficult for people to know how much salt they were eating.
Cash chairman Professor Graham MacGregor, from the Barts and The London School of Medicine and Dentistry, said: "It is the very high levels of unnecessary salt that are added to our food that puts up our blood pressure and leads to thousands of people needlessly dying of strokes, heart attacks and heart failures every year.
"The shockingly high levels of salt in many of these products mean that many people in the UK are consuming huge amounts of salt when they enjoy a curry.
"We urge all these manufacturers and providers to reduce their salt content immediately."
Cash nutritionist Katharine Jenner said: "A regular curry night is becoming a British institution, making these high salt levels extremely worrying.
"This survey shows salt can be hidden behind all the spices and chilli in your curry, even in side dishes and sauces. Add to this the lack of clear labelling on packaging and in takeaway restaurants, and it makes it very hard for consumers to choose a healthy option."
British Heart Foundation spokeswoman Mubeen Bhutta said: "The level of salt in some of these curries is frankly outrageous, but it's often tucked away behind unhelpful food labels where it's difficult to spot.
"Food manufacturers should give shoppers the whole truth about what they are putting in their baskets. We believe that universal front-of-pack labelling including traffic light colours, the words high, medium and low and guideline daily amounts are key to helping people easily understand what's in the food and drink they take to the tills."