Common causes of thirst


You will usually feel thirsty because you're notdrinking the amount of fluid your body needs. This may be because you've been sweating heavily or you've lost fluid because you have diarrhoea and are vomiting .

You can soon quench your thirst and restore the fluid balance in your body by having a drink and ensuring you remain well hydrated.

It'sparticularly important to stay well hydratedduring hot weather, while exercising and while you're unwell with vomiting and diarrhoea. Eatingsalty or spicy foods can cause you to suddenly feel thirsty.


If you feel thirsty all the time, it could be a sign of diabetes particularly if you also have other symptoms such as needing to urinate frequently, extreme tiredness (fatigue) and unexplained weight loss .

Diabetes is a lifelong condition that makes it difficult to control the level of sugar (glucose) in your blood. The high levels of glucose can mean your kidneys need to produce more urine to help pass the glucose out of your body. This can make you feel thirsty because your brain is telling you to drink more to make up for the fluids you've lost.

If you feel thirsty all the time and have other symptoms, your GP will probably carry out a blood glucose test to see whether you have diabetes.


Feeling thirsty, as well as urinating more often than usual, is a common symptom in pregnancy and usually nothing to worry about. You should be screened for this as part of your antenatal care if you're at risk.


Excessive thirst cansometimes be a side effect of certain types of medication, including lithium, certain antipsychotics and diuretics (water tablets).

If you think a particular medicine is causing your thirst, it may be possible to change to a different medicine or reduce your dose. Speak to your GP about this.

Content supplied by the NHS Website

Medically Reviewed by a doctor on 21 Dec 2018