Oral Rehydration Solutions for Diarrhea, Vomiting and Dehydration: What They Are and Who Needs Care

Urgent signs first

Severe dehydration is a life-threatening emergency. [1] In the US, call 911 for someone who loses consciousness, is confused, has a seizure or does not improve despite treatment. [1] The NHS (UK) lists signs of shock after dehydration as blue, grey, pale or blotchy skin, cold skin, fast breathing, confusion or unusual sleepiness, and says to call 999 or go to A&E. [2] Contact a clinician promptly if a baby, young child or older adult has signs of dehydration, if there is blood in the stool, or if someone cannot keep fluid down. [3][4]

Short answer

An oral rehydration solution (ORS) is a medical-style drink that replaces water and the salts lost in diarrhea and vomiting. WHO describes it as a mixture of clean water, sugar and salt, absorbed in the small intestine, which replaces the water and electrolytes lost in the stool. [5] The NHS says a pharmacist can recommend oral rehydration powders to mix with water. [2] This page does not give recipes or amounts: use the directions on a pharmacist-recommended product or your clinician's advice.

What is lost, and why it matters

During diarrhea, water and electrolytes (sodium, chloride, potassium and bicarbonate) are lost through liquid stool, vomit, sweat, urine and breathing, and dehydration occurs when these losses are not replaced. [5] The NHS says that if you are being sick or have diarrhea and are losing too much fluid, you need to put back the sugar, salts and minerals your body has lost. [2] Plain water does not contain a significant amount of electrolytes. [6]

What the sources recommend

Types of ORS: what is and is not known

WHO has recommended an ORS osmolarity of less than 270 mOsm/L since 2004. [8] A 2016 Cochrane review of 35 trials (4,284 people, mostly children) compared rice- or other polymer-based ORS with standard glucose-based ORS. [8] It found that polymer-based ORS may shorten diarrhea by about eight hours, but the evidence was low quality and results varied. [8] The authors said polymer-based ORS showed advantages over higher-osmolarity glucose ORS, and that the comparison with lower-osmolarity ORS was underpowered. [8] So the research does not show one winner among properly made ORS products.

ORS compared with other drinks

In a randomized trial of 72 euhydrated, fasted men who were not ill, drinking an oral rehydration solution produced less urine over four hours than still water did, while a sports drink was not different from water. [9] That trial measured fluid retention in people who were not dehydrated, not recovery from illness, so it cannot tell us how the drinks compare for diarrhea. For children with illness, the NHS says not to give fruit juice or fizzy drinks, which can make diarrhea or vomiting worse. [2] Caffeine and alcohol dehydrate. [2] A deeper comparison is on Electrolyte powder vs sports drink vs oral rehydration solution.

Who needs a clinician, not home care

• Babies under 12 months. The NHS says to call 111 (UK) if you are worried about a baby under 12 months. [3]
• Children. MedlinePlus says diarrhea in babies and children can be serious and needs to be treated differently than in adults. [4] See Electrolytes for children and infants.
• Older adults, weakened immune system, or conditions that raise dehydration risk. The NHS says to speak to a pharmacist. [3] Older adults and people with diabetes are at higher risk. [1]
• Kidney, heart or liver disease, or taking diuretics. These change how the body handles fluid and electrolytes. [10] Ask your clinician before using any electrolyte product, and see Medication interactions.
• Illness lasting longer than expected. The NHS says to call 111 for diarrhea for more than 7 days, vomiting for more than 2 days, or bloody diarrhea. [3]

WHO also advises consulting a health professional for persistent diarrhea, blood in the stool or signs of dehydration. [5] Do not give children under 12 medicine to stop diarrhea unless a clinician advises it. [3]