How to manage Wegovy injections while experiencing illness or fever

With illness or fever, focus on fluids, simple foods, and rest; if vomiting or dehydration is significant, contact your service before taking the next dose. For stomach bugs, clinicians often advise delaying until you’re tolerating fluids and food again. If you’re booked for procedures with sedation or anaesthesia, your team may adjust timing to reduce aspiration risk — always follow their specific instructions.

Why illness matters for Wegovy dosing

Short-term illness, such as fever or stomach upset, can affect how well Wegovy (semaglutide) is tolerated. NICE TA875 and NHS England’s 2025 weight-management framework note that semaglutide remains active in the body for around a week, so short interruptions don’t usually alter progress. The main risk during illness is dehydration, which can worsen side effects like nausea, dizziness, or fatigue. Pausing until normal eating and drinking resumes keeps treatment safe.

Managing mild illness

If you have a cold, mild fever, or sore throat but can still eat and drink, you can continue injecting on schedule. NHS clinicians recommend maintaining hydration and eating light, balanced foods such as soups, porridge, or fruit. Appetite often dips slightly during illness, and this temporary reduction is harmless. Avoid very fatty or spicy meals, which can worsen nausea. Some users find morning injections easier during recovery, as symptoms are milder earlier in the day.

When to delay a dose

If you cannot tolerate fluids, experience repeated vomiting, or have diarrhoea lasting more than 24 hours, delay the next dose until symptoms settle. NICE and MHRA guidance warn that taking semaglutide while dehydrated may cause low blood pressure or kidney strain. In these cases, skip the planned injection and restart once you can drink and eat without discomfort. If illness lasts longer than a few days, contact your clinician — they may hold the next dose or check kidney and electrolyte levels before resuming.

Hydration and recovery

Hydration is the key focus during recovery. NHS and SMC guidance recommend drinking water or low-sugar electrolyte drinks in small, frequent sips. For older adults or those on blood pressure tablets, extra care is needed to prevent dizziness when standing. Clinicians may advise pausing diuretics or certain medications temporarily if dehydration risk is high. When appetite returns, introduce small meals with lean protein, fruit, and whole grains. Avoid fasting or skipping meals after illness; restoring nutrition helps stabilise semaglutide’s effects and energy balance.

Preparing for medical procedures

For operations or sedation, NHS and MHRA (2024) guidance advises pausing Wegovy at least one week before the procedure. Because semaglutide slows stomach emptying, residual food in the stomach increases aspiration risk under anaesthesia. Inform your anaesthetist about your treatment during pre-operative checks so they can confirm timing. After surgery, resume Wegovy only when eating normally and free of nausea. Clinicians may adjust timing for larger procedures or those involving the gastrointestinal tract.

Monitoring appetite and energy

During illness, appetite loss and lower fluid intake may make people feel unusually weak. NHS teams encourage slow reintroduction of soft foods such as yoghurt, soup, or eggs to maintain protein intake. If you use other diabetes or weight-related medicines, your clinician might temporarily adjust their doses to prevent hypoglycaemia. Appetite and energy levels should gradually return as you recover; if fatigue or nausea persist beyond a week, a review may be needed before restarting the full dose schedule.

When to contact your team

Contact your clinic or pharmacist if:

• You can’t keep fluids down for 24 hours or more.

• You experience severe abdominal pain, dizziness, or prolonged vomiting.

• You’re admitted to hospital or scheduled for urgent surgery.

• You feel uncertain about when to resume your weekly dose.

NHS weight-management services often have on-call advice lines for these questions. Clinicians prefer early updates rather than discovering problems at the next review.

What research shows about short treatment gaps

STEP and SELECT trials, reported in Nature Medicine and Lancet (2024), showed that short pauses due to illness did not affect long-term outcomes. Participants who resumed once recovered continued to lose weight and maintain cardiovascular benefits. NICE TA875 and SMC reviews confirm that missing one or two weekly doses doesn’t require restarting from the lowest dose, provided treatment resumes promptly and consistently.

Practical examples from NHS services

In NHS weight-management clinics, staff often use a “pause and protect” rule: pause injections if unwell, protect hydration, and resume when stable. Pharmacists may also advise having a small hydration plan ready — oral rehydration salts or low-sugar drinks — especially for those living alone or managing chronic conditions. Many users find it reassuring to plan ahead by keeping fluids and soft foods available at home.

The essential point

During illness or fever, prioritise fluids, nutrition, and rest. Wegovy can be paused safely until recovery. Delay doses if vomiting or dehydration occur, and follow your clinician’s timing for surgery or sedation. NICE, NHS, MHRA, and SMC guidance agree: temporary pauses are safe and protect wellbeing. Clear communication and good hydration ensure a smooth, effective return to your regular schedule once you’re well.