Dehydration can come about through a range of common scenarios, meaning you can easily find yourself dehydrated on a hot day or if you’ve been doing a lot of exercise. But despite it being so common, many of us don’t recognise the symptoms until they’re having a big impact on us.¹
It’s important to understand dehydration because our bodies require a certain level of fluids to operate effectively. For example, water helps us to regulate our temperature, digest food and perform cellular functions.¹ When you’re dehydrated, these processes and others may be affected, causing a range of symptoms.
Unfortunately, dehydration doesn’t look the same every time for everyone – it can vary depending on how dehydrated you are, your age and your pre-existing health.¹ As a result, dehydration signs may not be noticed or may be mistaken for other common complaints, such as fatigue, stress or a general lack of sleep.
What are the symptoms of dehydration?
In mild cases, the signs of dehydration may be easy to miss, while more moderate dehydration can produce clearer physical effects. Understanding these symptoms can help you identify dehydration earlier and take appropriate steps to address it.
Thirst
Thirst is one of the primary signals the body uses to indicate that it needs more fluids.¹ It’s triggered when the body’s fluid balance begins to decrease.
While thirst is a useful indicator, it may not always appear immediately at the earliest stages of dehydration. It’s also the case that some people may find it harder to notice feelings of thirst, particularly if you’re distracted by other activities.
Because of this, relying solely on thirst might not be the best option to let you know when it’s time to rehydrate. Drinking water at regular intervals instead, even before you feel thirsty, can help to support consistent fluid levels.
Urine changes
Changes in urine colour and frequency are often considered one of the most practical indicators of dehydration.¹ Typically, well-hydrated people produce urine that is pale yellow in colour. Darker urine may suggest that your body is low on water and that it’s time to drink some fluids.
In addition to colour, a decrease in how often you urinate may also be a sign of dehydration.¹ Keeping an eye on these changes can provide a simple way to know whether your body may need more fluids.
Dizziness and fatigue
Dizziness, light-headedness and fatigue are common symptoms that may be associated with dehydration.¹ When the body lacks sufficient fluids, blood volume can decrease, which may impact circulation and the delivery of oxygen and nutrients throughout the body.
However, it’s important to note that these symptoms can also have other causes, such as low blood sugar, stress or lack of sleep.
If dehydration is the cause, increasing fluid intake may help to improve symptoms within a short period of time.¹ If these symptoms persist, it’s worth checking in on other needs such as sleep and nutrition, or speaking to a pharmacist about other potential causes.
Dry lips or mouth
A dry mouth or chapped lips can be another sign that the body is not receiving enough fluids.¹ Saliva production may decrease when hydration levels are low, leading to a dry or sticky sensation in the mouth.
This symptom may become more noticeable in warm environments, during physical activity or after extended periods without drinking water. Regular fluid intake can help to maintain moisture levels in the mouth and reduce discomfort.
Headache
Headaches are sometimes linked to dehydration, although they can occur for many different reasons.¹ Changes in hydration levels may influence blood flow and neurological function, which can contribute to the onset of headaches.
If dehydration is the cause, drinking water may help to relieve the headache within an hour or two.¹ If the discomfort doesn’t improve, the headache may be due to another underlying factor. Regardless, maintaining proper hydration remains beneficial for overall health.
Signs of dehydration in babies
Dehydration in babies and young children can be more difficult to identify, as they’re not able to speak up and let you know directly if they’re thirsty.¹ This makes it especially important for caregivers to pay attention to physical and behavioural signs.
Common indicators may include
- Fewer wet nappies
- A dry mouth
- A lack of tears when crying
- Reduced activity levels.¹
In more advanced cases, the soft spot on a baby’s head (fontanelle) may appear sunken. Because infants are more vulnerable to dehydration, monitoring their fluid intake and overall condition is particularly important, especially during illness or warm weather.
Most of the time, dehydration isn’t serious, but it’s worth being aware of the symptoms so you can limit discomfort and keep yourself well hydrated. Pay particular attention when looking after young children or vulnerable adults who may not be able to communicate when they’re feeling thirsty – and remember, little and often is a good way to head dehydration off before you feel the effects.
References
- NHS (National Health Service). Dehydration. https://www.nhs.uk/conditions/dehydration/
- Mayo Clinic. Dehydration – Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/dehydration/symptoms-causes/syc-20354086
- Cleveland Clinic. Dehydration. https://my.clevelandclinic.org/health/diseases/9013-dehydration
- Harvard Health Publishing. Symptoms of dehydration: What they are and what to do if you experience them. https://www.health.harvard.edu/healthy-aging-and-longevity/symptoms-of-dehydration-what-they-are-and-what-to-do-if-you-experience-them
- Royal Children’s Hospital Melbourne. Dehydration fact sheet. https://www.rch.org.au/kidsinfo/fact_sheets/Dehydration/
