Are Malnutrition, Dehydration & Medicines on Your Safety Radar?

If you work in a UK care home, you’re already juggling a lot: complex medicines, changing health needs, family expectations, inspections…the list goes on.

But there’s a quiet safety risk that often hides in plain sight:

Malnutrition + dehydration + multiple medicines = a perfect storm for harm.

NICE now estimates that 1 in 10 people over 65 are at risk of malnutrition, and the impact on medicines is far from trivial. It affects how drugs are absorbed, distributed, metabolised and excreted – in other words, how they work and how safe they are NICE CKS Adult Malnutrition, 2024.

This blog looks at what this means for care homes, and how you can build malnutrition and dehydration into everyday medicines safety.

Why malnutrition and dehydration matter for medicines

u’re short of time on a medication round, it’s easy to focus on the MAR and miss the person in front of you.

But if that person is quietly losing weight, eating very little, or barely drinking, several things start to happen:

Less body water (dehydration) means some drugs become more concentrated in the bloodstream.
Less body fat and muscle (malnutrition) alters how medicines are stored and released.
Reduced liver and kidney function can slow drug breakdown and excretion.
Poor intake overall can make some medicines less effective, especially those relying on food or fluid for absorption.

NICE is clear that adults who are malnourished or at risk should have a personalised nutrition care plan and, where appropriate, coordinated input from dietitians, nurses, pharmacists and others NICE CKS.

In a care home, that means malnutrition and dehydration are not “extra” tasks – they’re core to safe medicines management.

Malnutrition and dehydration directly change how medicines work.
Older residents with frailty and multiple long‑term conditions are at particularly high risk.
NICE recommends a structured approach: screening, care plans and regular monitoring.
For care homes, nutrition and hydration are medication safety issues, not just “wellbeing nice‑to‑haves”.

Spotting early warning signs in everyday care

You don’t need a complex tool to notice that something’s not right.

Typical red flags include:

Possible malnutrition

Unplanned weight loss
Looser clothing or rings
Poor appetite or leaving most meals
Fatigue, weakness, “slowing down”
Poor wound healing or pressure areas that don’t improve

Possible dehydration

Dry mouth, cracked lips
Sunken eyes
Dark, strong-smelling or reduced urine
New or worsening confusion
Dizziness, postural drops, low blood pressure

NICE recommends regular screening for malnutrition risk, usually using MUST (Malnutrition Universal Screening Tool) – widely supported by BAPEN and referenced in your resources. A MUST score of 1 = medium risk; 2 or more = high risk.

Screening is important, but your day‑to‑day observations are just as valuable. Those “small concerns” you jot in the notes – not finishing meals, drinking less, looking more tired – are often the first clues that medicines may soon become unsafe.

Look for simple physical and behavioural changes: weight, clothing fit, appetite, fluid intake, confusion.
Use a validated tool such as MUST to formalise risk assessment (BAPEN).
Combine structured screening with staff “gut feeling” – both matter.
Capture concerns early so they can feed into medication review and care planning.

How malnutrition and dehydration change pharmacokinetics (how meds work)

It’s easy to think of medicines as fixed: 20 mg is 20 mg.

In reality, dose is only half the story. The other half is what the body does with the medicine – pharmacokinetics:

Absorption – getting into the bloodstream
Malnutrition and dehydration can slow gut movement and reduce blood flow to the gut. This can mean:
- Delayed absorption (drug takes longer to work).
- Unpredictable levels, especially with medicines that have a narrow therapeutic window.
Distribution – where the drug goes
Many drugs bind to proteins (especially albumin) and distribute into body water or fat. When a resident is malnourished or dehydrated:
- Less body water → higher concentration of water‑soluble drugs.
- Low albumin → more “free” (active) drug circulating, increasing side‑effect risk.
Metabolism – how the liver breaks drugs down
Poor nutrition and chronic illness can reduce liver function:
- Drugs may be metabolised more slowly.
- Levels can build up even when doses haven’t changed.
Excretion – how the kidneys clear drugs
Dehydration and age‑related decline both reduce kidney function:
- Drugs stay in the body longer.
- Toxicity risk rises, especially with renally‑cleared drugs.

NICE emphasises that in people at medium or high risk of malnutrition, we should actively manage complications and consider how nutrition support, fluid balance and medicines interact NICE CKS.

Malnutrition and dehydration affect absorption, distribution, metabolism and excretion.
The same dose can lead to very different drug levels in a malnourished or dehydrated resident.
Older people on multiple medicines are especially vulnerable to toxicity and treatment failure.
Medicines reviews should always consider current nutrition and hydration status.

High‑risk medicines and patterns to watch for

Some medicines become noticeably higher risk when nutrition or hydration are poor. Your carousel rightly highlights several:

Cardiac drugs – especially digoxin and some blood‑pressure medicines.
Lithium – very sensitive to changes in fluid and sodium balance.
Diuretics – can worsen dehydration and electrolyte imbalance.
Diabetes medicines – risk of blood sugar swings if food intake changes.
Some antibiotics and other renally‑cleared drugs – higher toxicity if kidneys are struggling.

Common examples of patterns seen in care homes:

A resident eats and drinks much less during an infection, but med doses stay the same.
A diuretic is continued despite diarrhoea, vomiting or very low oral intake.
Lithium or ACE inhibitors are not reviewed during an acute illness.
Blood sugars become erratic because diabetes medicines weren’t adjusted when appetite dropped.

NICE and other UK guidance support the principle of “sick day rules” for certain drugs – temporarily holding or adjusting doses during acute illness or significant dehydration, under prescriber advice.

Section summary – key points

Some medicines are much less forgiving when nutrition or hydration change.
Watch for cardiac drugs, lithium, diabetes medicines, diuretics and nephrotoxic drugs.
Link acute illness, reduced intake and any new side effects back to the medication list.
Discuss “sick day rules” and individual plans with prescribers for high‑risk residents.

Practical actions for care homes: what good looks like

NICE guidance is clear that people at risk of malnutrition should receive oral nutrition support and a clear plan, before jumping straight to supplements or tube feeding NICE CKS.

In a care‑home setting, that translates into a series of simple, practical steps.

a) Monitor intake and weight

Record food and fluid intake for anyone who is unwell or on high‑risk medication.
Weigh regularly (at least monthly for stable residents; more often if at risk).
Escalate sustained weight loss or very low intake to the nurse in charge or manager.

b) Optimise food first

Using NICE and the Malnutrition Pathway:

Offer small, frequent, nutrient‑dense meals and snacks, not just three bigger meals.
Fortify foods (e.g. full‑fat milk, cheese, cream, butter, milk powder) where appropriate.
Adapt textures for dry mouth or chewing difficulties – but be mindful that very diluted textures can be low in energy and protein.
Work with preferences: favourite foods, finger foods, fortified drinks.
Encourage adequate hydration – regular sips, jugs in reach, preferred drinks and temperatures.

c) Consider oral nutritional supplements (ONS) appropriately

NICE advises that ONS are usually for people at high risk (MUST ≥2) when food alone is insufficient NICE CKS:

They should be in addition to, not instead of, meals.
Quantity, flavour and type should be individualised.
Use local dietetic guidance and review within 4–12 weeks.
Stop or adjust if goals are met, intake improves or they are not tolerated.

d) Link nutrition with medicines review

Whenever malnutrition or dehydration is suspected:

Review medicines with the prescriber, pharmacist or PCN clinical team.
Highlight high‑risk drugs (e.g. diuretics, ACE inhibitors, lithium, metformin, SGLT2 inhibitors, digoxin).
Agree any dose adjustments, temporary holds, monitoring (e.g. U&Es, lithium levels, blood sugars).
Clarify what should trigger urgent reassessment.

Section summary – key points

Start with food, fluids and environment before (or alongside) supplements.
Use ONS for clearly‑defined high‑risk residents, with goals and review dates.
Make nutrition and hydration part of every medication review.
Collaborate with dietitians, GPs, pharmacists and speech and language therapists where available.

Good intentions only go so far if they’re not written down or handed over safely.

Documentation and handover

Your carousel rightly emphasises:

Recording all observations: intake, weight, hydration, side effects, behaviour changes.
Documenting advice sought and actions taken around medication adjustments.
Clear handovers so that nutrition, hydration and medicines plans don’t get lost between shifts.

Accurate records also support compliance with CQC expectations on medicines safety and nutrition in adult social care.

When to escalate urgently

Some situations need immediate medical review rather than a routine note for the next GP round. These include:

Rapid deterioration in physical or mental state.
Signs of severe dehydration (very low output, confusion, tachycardia, hypotension).
Significant, unexplained weight loss over a short period.
New confusion, agitation or drowsiness that could indicate drug toxicity.
Any serious concern from family or staff that “something is very wrong”.

In those moments, your clinical judgement – backed by clear observations – is crucial.

Good documentation and handover turn observations into safe, consistent care.
Record what you see, what you did and any advice received.
Know your red‑flag signs and routes for urgent escalation.
Strong records help protect residents, staff and the service during inspections.

Documentation, handover and when to escalate

Compassion, choice and person‑centred care

Finally, it’s important to remember that behind every care plan, MUST score and MAR chart is a person with preferences, fears and history.

NICE encourages individualised goals – not just “gain weight” but “feel stronger walking to the dining room” or “have enough energy to see my grandchildren” NICE CKS.

In practice, that means:

Involving residents and families in decisions about food, drinks and medicines.
Respecting cultural, religious and personal preferences.
Being honest about risks while focusing on what matters most to the person.
In palliative or end‑of‑life care, shifting goals to comfort, symptom control and quality of life.

Your role isn’t just to deliver tablets and count fluids; it’s to support people to live as well as possible, for as long as possible, in the place they call home.

Goals should be meaningful to the resident, not just numbers on a chart.
Choice, dignity and cultural preferences remain central, even when risks are high.
In palliative care, the focus may shift from “treating” malnutrition to easing symptoms.
A caring, curious conversation is often the best starting point for safer medicines.

Final take‑aways for your next shift

Bringing it all together:

Think nutrition and hydration every time you think medicines.
Use simple observations plus tools like MUST to spot risk early (BAPEN).
Understand that malnutrition and dehydration alter how drugs work – particularly for cardiac, diabetes, lithium and renally‑cleared medicines.
Start with food first, then consider ONS in line with NICE guidance and local policies.
Build nutrition and hydration into regular medication reviews, documenting any changes.
Escalate urgently if you see rapid deterioration, severe dehydration, marked weight loss or signs of drug toxicity.
Keep the person at the centre: their goals, preferences and quality of life matter most.

For more detailed guidance, you can explore:

You don’t have to fix everything at once. But each time you link a resident’s eating, drinking and weight to their medicines, you’re putting safety – and compassion – firmly back on the radar.