Vitamins for dehydration: what to know

Dehydration occurs when the body loses more fluid than it takes in. Water loss may happen with vomiting, diarrhoea, sweating, fever, or simply not drinking enough. A multivitamin cannot restore the fluid volume circulating in the body. Some oral rehydration products contain water, salts, and glucose to help the intestine absorb fluid; they are different from vitamin supplements. If poor intake has lasted, a clinician can assess whether a genuine nutrient deficiency is also present. Dark urine, constipation, or cloudy urine can have several causes, so they should not be interpreted as proof of dehydration on their own.

Take frequent small sips of water and consider an appropriate oral rehydration solution when fluid loss follows vomiting, diarrhoea, heavy sweating, or heat exposure. Continue with light foods as tolerated. Avoid relying on energy drinks or high-dose vitamin products, which may upset the stomach and do not correct the underlying fluid deficit. Follow preparation instructions on any rehydration product. A pharmacist or GP can help choose an option if you have kidney disease, heart disease, are pregnant, or are giving fluids to a child. A recent illness such as gastroenteritis or heat exhaustion may need attention alongside rehydration.

Seek urgent medical help for confusion, fainting, severe weakness, inability to keep fluids down, very little urine, or difficulty waking. Prompt assessment is also sensible when dehydration follows ongoing diarrhoea, repeated vomiting, or significant heat exposure, or when symptoms are not improving with sipping fluids. People who are older, pregnant, very young, or living with a long-term illness can worsen more quickly. A clinician may need to give fluids through a vein and check electrolytes or the cause of the loss.

Could a medicine or illness be causing my fluid loss? Do I need an oral rehydration solution rather than a vitamin supplement? Should my kidney function or electrolytes be checked?