Together, these two symptoms have a short list of causes and one obvious first test.
Assessed by a GMC-registered GP, not a symptom checker
Honest about what needs to be seen in person
Tests and referrals arranged where they are needed
Your NHS records in the room, with your consent
Care led personally by Dr Khan
Attentive, unhurried care that listens properly
Five-star Google reviews from the people we have looked after
Registered with the Care Quality Commission
Seek same-day medical care for excessive thirst and urination alongside:
That combination may indicate diabetic ketoacidosis, which is a medical emergency. In a child or young adult with new thirst and weight loss, do not wait — this can be new type 1 diabetes and it develops quickly.
Otherwise, thirst and frequent urination persisting more than a couple of weeks warrants a prompt blood test rather than watching.
Passing more urine because you are drinking more is normal. What is not normal is drinking more because you cannot stop feeling thirsty, particularly if you are also getting up at night to pass urine when you never used to.
The two symptoms together have a considerably shorter list of causes than either alone, and the first test is straightforward.
The main one — diabetes. High blood glucose pulls water into the urine, which causes both the urination and the thirst that follows it. This is the classic presentation and the reason the first step is always a blood test.
Urinary rather than metabolic — urinary infection and cystitis cause frequency and urgency but usually with burning, and without the thirst. An enlarged prostate causes frequency, particularly at night, again without thirst.
Other causes — high calcium, sometimes from an overactive parathyroid; kidney disease; medication, particularly diuretics, lithium and SGLT2 inhibitors; excessive caffeine or alcohol; and diabetes insipidus, which is rare and unrelated to blood sugar.
Anxiety and habit — dry mouth from anxiety, or simply drinking a great deal out of habit, which then causes the urination. Common, and worth distinguishing before investigating further.
Persistent excessive thirst is diabetes until something else explains it. That is not alarmism; it is simply the order in which this symptom is worked through, and the test is cheap, quick and definitive.
An HbA1c gives an average of the last three months. A finger-prick or a pharmacy check gives an answer today. Either is more useful than another week of wondering.
People are poor judges of their own fluid intake in both directions.
Consistently more than about three litres a day, with matching output, warrants investigation.
These feel similar and mean quite different things:
Do not quench it with fruit juice, squash, energy drinks or fizzy drinks. If the cause is undiagnosed diabetes, sugary drinks drive the blood glucose higher, which increases thirst further — a genuine and fairly vicious loop that some people spend weeks in. Water only, until you know.
This applies particularly to children, teenagers and young adults, in whom type 1 diabetes can develop over days rather than months.
That combination is diabetic ketoacidosis. It is a medical emergency, it can develop very quickly, and it is frequently mistaken for a stomach bug. Say "I am worried about diabetes" on arrival — a finger-prick test takes seconds.
The distinguishing question is which came first — thirst driving the drinking, or drinking driving the urination. Genuine thirst that persists despite drinking is the pattern that points to diabetes.
Testing is simple and decisive. HbA1c gives your average blood glucose over three months and is not affected by what you ate yesterday. We measure kidney function and calcium alongside, since both feature on the list, and review your medication.
Where diabetes is confirmed, the consultation covers what type it is likely to be, treatment, and referral into structured support. Where results show prediabetes, that is the stage at which it is frequently still reversible, and the conversation focuses on what actually achieves that.
Consistently more than about three litres a day, when you are not in hot weather or exercising heavily, and when it comes with passing correspondingly large volumes of urine. The pairing is what matters — drinking a lot because you have decided to be healthy, without any change in how often you go, is a habit rather than a symptom.
Getting up more than once a night to pass urine, in someone who did not use to, is a useful and objective marker.
It is the first thing to exclude, and it is the commonest cause. The classic combination is thirst, passing large volumes of urine, tiredness, and weight loss, sometimes with blurred vision, recurrent thrush or slow-healing cuts.
An HbA1c blood test settles it. If it is diabetes, finding it now rather than in six months genuinely matters — much of the harm from diabetes accrues while it is undiagnosed.
Chiefly by speed. Type 1 typically develops over days to a few weeks, with marked thirst, dramatic urination, and rapid unintentional weight loss, most often in children, teenagers and younger adults — though it can begin at any age.
The warning signs that make it an emergency are vomiting, abdominal pain, deep rapid breathing, breath smelling of pear drops, and drowsiness. That is ketoacidosis, it develops fast, and it is routinely mistaken for gastroenteritis. Go to A&E the same day and ask for a blood glucose check.
No, and the distinction is useful. A dry mouth with normal urine output points to reduced saliva rather than to fluid balance — usually from mouth-breathing overnight, snoring, medication, dehydration, or occasionally Sjögren's syndrome, where dry eyes accompany it. True thirst comes with passing more urine. That is the pairing that points at diabetes.
Frequently. Diuretics cause both thirst and increased urination by design. Lithium can reduce the kidney's ability to concentrate urine, causing genuinely large volumes — worth flagging if you take it. Antidepressants and antihistamines tend to dry the mouth rather than cause true thirst. Steroids raise blood glucose and can produce the full diabetic picture.
Less commonly, yes. A raised blood calcium level causes thirst, frequent urination, constipation and low mood, and it is picked up on a routine blood test — it is worth checking because it is easily missed. Chronic kidney disease can impair urine concentration. Diabetes insipidus — unrelated to sugar diabetes — causes very large volumes of extremely dilute urine and is rare but real.
HbA1c first, alongside kidney function and electrolytes including calcium, full blood count, thyroid function and urine testing. That combination identifies almost every cause of genuine excessive thirst, and can be arranged the same week.
Any of the ketoacidosis features — A&E today. Thirst with rapid weight loss, particularly in someone young — same day. Thirst with tiredness and frequent urination over weeks — this week. Mild dry mouth with normal urine output and no other symptoms — routine, but still worth a conversation and a test.
Clinically reviewed by Dr Mohammad Zubair Khan, GMC 7563469
Last reviewed
August 23, 2026
On this page
Ongoing
Time to be seen
Appointment length
Your NHS record in the room
Written treatment plan
Told when a test isn’t needed
Cost
Same day, usually
20 minutes
Yes, with your consent
Included
Yes, and told why
£40 for 20 minutes
Varies by practice
Typically 10 minutes
Yes, your full record
Not routinely
Usually
Free
Same day
Often 10 to 15 minutes
Usually not
Sometimes charged
Varies by provider
Often a subscription
Same-day access is usually available, from 6am to 10pm, seven days a week. You choose a time that suits you rather than waiting on hold at 8am.
Yes. Care is led personally by Dr Mohammad Khan, so you are not passed between clinicians. Continuity is the point of a small practice: someone who knows your history and is listening attentively rather than working through a checklist.
Yes, with your consent. We can access your Summary Care Record during the consultation, so your current medications, allergies and significant history are in the room. That means fewer questions you have already answered elsewhere, and safer prescribing.
No. We are not here to replace GPs, only to support them. Your NHS practice remains responsible for your ongoing care, and with your consent we write to them after the consultation. We are useful when you need to be seen sooner, or want more time than a standard appointment allows.
Twenty unhurried minutes and a comprehensive assessment. A written treatment plan is included, along with any prescription, sick note or referral letter arising from the consultation, at no extra charge.
£40 for 20 minutes, self-pay. Membership is optional and never required. Priced for fairness, because we are not here to charge extortionate amounts for access to a doctor.
It means the diagnosis can usually be made from your history and photographs, and that treatment can be arranged safely without examining you. Where a condition is not marked treatable online, it is because examination is the diagnosis — listening to a chest, feeling an abdomen, examining an ear or a joint — or because a procedure or device is needed.
Yes, where there is a genuine bacterial infection — cellulitis, impetigo, bacterial urine infections, confirmed strep throat. We will also frequently tell you that you do not need one. Most sore throats, coughs, colds and earaches are viral, and an antibiotic gives you the side effects with none of the benefit.
If your problem turns out to be genuinely outside what we can do remotely, the doctor will tell you straight away, point you to the right service, and refund your fee in full. We would rather do that than fill twenty minutes to justify the charge.
Call 999 or go to A&E — do not book an online appointment and do not wait for a reply to an email. For urgent problems that are not emergencies, NHS 111 is available 24 hours a day, online or by phone, and can direct you to the right service.
Patient reviews
