Last updated: October 2026
Yes, the flu jab can make you tired. Tiredness is a common, mild side effect, along with a sore arm, a headache, aching muscles and a slight temperature. They usually start within a few days and the NHS says they get better within 1 to 2 days. Call 999 for signs of a severe allergic reaction, or 111 if worried.
Below: each side effect and how long it lasts, what helps, symptoms a week later, the flu and COVID jabs together, and who can get the vaccine free this winter.
Common flu jab side effects
All adult flu vaccines in the UK are injections. The NHS says their most common side effects are mild and get better within 1 to 2 days. The Green Book, the UK’s official vaccine guide for health professionals, lists these as the most commonly reported:
| Side effect | How common | Usually lasts |
|---|---|---|
| Sore, red or swollen arm where the jab went in | Very common (more than 1 in 10 people) | 1 to 2 days |
| Small painless lump where the jab went in | Can happen | 1 to 2 days |
| Feeling tired | Very common with some vaccines, less common with others | 1 to 2 days |
| Headache | Very common | 1 to 2 days |
| Aching muscles or joints | Aching muscles very common; aching joints common | 1 to 2 days |
| Slight temperature or shivering | Common with some vaccines | 1 to 2 days |
| Feeling generally unwell or off your food | Very common with some vaccines | 1 to 2 days |
How common each one is varies by vaccine; these figures come from the UK patient leaflets for this season’s vaccines. The children’s nasal spray has slightly different side effects (see children and pregnancy).
Can the flu jab make you tired?
Yes. The Green Book lists tiredness as a common side effect, and the leaflet for the cell-based flu vaccine lists it as very common (more than 1 in 10 people). The NHS also lists feeling tired among the most common side effects of vaccines in general.
The vaccine works by prompting your immune system to make its own protection (antibodies). Feeling tired, achy or a bit under the weather for a day or so is a common part of that response. It isn’t a sign you’ve caught flu.
How long does the tiredness last?
Usually 1 to 2 days. The Green Book says these symptoms usually disappear within 1 to 2 days without treatment. If you’re still exhausted after a few days, something else is more likely, such as a cold, poor sleep or the darker evenings. See why am I always tired? and tired in winter.
What helps
- Rest. Take it easy for the rest of the day. If you nap, keep it short (see power naps) so it doesn’t spoil your night’s sleep.
- Drink plenty of fluids, especially if you feel hot or shivery.
- Pain relief if you need it. For aches and a raised temperature, the NHS suggests paracetamol or ibuprofen, and after a COVID-19 jab it advises rest and paracetamol. For a child with a high temperature after a vaccine, it suggests plenty to drink and liquid paracetamol or ibuprofen for children. Follow the pack instructions and ask a pharmacist if unsure. Don’t give aspirin to under-16s.
For aches with other causes, see body aches and tension headaches.
How soon do side effects start and how long do they last?
- Within minutes: a severe allergic reaction, which is very rare. The person who vaccinates you is trained to treat it immediately.
- Within the first 3 days: sore arm, tiredness, headache, aches or a slight temperature. The leaflet for the high-dose vaccine, which many people aged 65 and over have, says most side effects appeared within 3 days and cleared within 3 days.
- After 1 to 2 days: the NHS says the common side effects get better.
Protection takes longer: the NHS says the vaccine usually takes up to 14 days to work.
Side effects a week later: is it the flu jab?
Common side effects appear in the first few days and pass quickly, so symptoms that start a week or more later are less likely to be from the jab. Colds and other bugs are common at this time of year, so the timing can be a coincidence.
- Something else you caught. The flu vaccine doesn’t protect against colds, and a cold, COVID-19 or sore throat can easily start the same week. See cold or flu?, sore throat remedies and cough at night.
- Flu caught before the jab worked. Flu usually shows 1 to 3 days after you catch it, and the vaccine takes up to 14 days to work.
- Something rarer. Guillain-Barré syndrome has been reported very rarely after flu vaccines, though a large UK study found no link with the vaccine and a strong link with flu-like illness itself. Tell a doctor straight away if you feel weak, find it hard to move around, or have numbness or tingling in your arms or legs.
If a symptom worries you, whenever it started, speak to a GP or pharmacist or call 111. You can also report it.
Having the flu and COVID jabs together
The NHS says you can have the flu vaccine at the same time as the COVID-19 and shingles vaccines. This winter’s COVID-19 vaccine is for people aged 75 or over (including those who’ll be 75 by 31 January 2027), people aged 6 months to 74 years with a weakened immune system, and care home residents for older adults.
The two jabs are usually given in different arms. The COVID-19 vaccine’s common side effects are similar (sore arm, tiredness, headache, aches, mild flu-like symptoms) and the NHS says they get better within a week. The Green Book notes that when the adjuvanted flu vaccine, often given to people aged 65 and over, is given with other vaccines, the side effects may add up. So you may feel more tired for a day or two.
Older adults aren’t usually given the RSV vaccine at the same appointment as the flu jab, unless a doctor or nurse thinks it’s needed.
Can the flu jab give you flu?
No. The NHS says the injected flu vaccines used in the UK don’t contain live flu viruses, so they can’t give you flu. The children’s nasal spray contains weakened live viruses that can’t multiply properly beyond the nose; the Green Book says they may cause mild cold-like symptoms, and the NHS says you can’t get flu from any flu vaccine.
Real flu comes on suddenly with a high temperature, exhaustion and often a dry cough, and recovery usually takes 2 to 7 days. Our cold vs flu guide explains the difference.
Serious reactions are rare
The NHS says serious side effects such as a severe allergic reaction (anaphylaxis) are very rare, and usually start within minutes. Call 999 if you or someone else:
- has sudden swelling of the lips, mouth, throat or tongue
- is breathing very fast or struggling to breathe
- has a tight throat or is struggling to swallow
- has skin, lips or tongue turning blue, grey or pale
- suddenly becomes very confused, drowsy or dizzy, or faints and can’t be woken
You can’t have the flu vaccine only if you’ve had anaphylaxis to a previous dose or an ingredient. If you have a high temperature on the day, wait until you feel better.
Children’s flu vaccine and pregnancy
Children’s nasal spray
Most eligible children have a quick, painless spray up each nostril. The NHS says the common side effects are mild and get better in 1 to 2 days: a blocked or runny nose, loss of appetite, feeling tired and a headache. The spray contains a small amount of pork gelatine, and an injection without gelatine is available. See the NHS children’s flu vaccine page or ask a GP or practice nurse.
Pregnancy
The flu vaccine is free at any stage of pregnancy. The NHS says studies show it’s safe then, it helps protect you and your baby in the first few months after birth, and it’s safe to breastfeed after having it. Ask your midwife or GP, or see the NHS flu vaccine page.
Who can get the flu vaccine free this winter (2026 to 2027)
In England, you can get the free NHS flu vaccine if you:
- are 65 or over (including those who’ll be 65 by 31 March 2027)
- are 18 to 64 with certain long-term conditions, such as asthma needing a steroid inhaler, diabetes, or heart or kidney disease
- are pregnant or live in a care home
- are the main carer for an older or disabled person, or receive carer’s allowance
- live with someone who has a weakened immune system
- are 16 or over and sleeping rough or staying in a hostel or night shelter
Frontline health and social care workers get it through their employer. Children aged 2 or 3 on 31 August 2026, school children from reception to year 11, and children from 6 months with certain conditions are offered it too. UKHSA confirms there are no changes to who’s eligible this season.
How to book: online or in the NHS App, at a pharmacy offering free NHS flu jabs, or through your GP surgery. The NHS advises having it as soon as you can; the last date is 31 March 2027. Scotland, Wales and Northern Ireland run their own programmes.
Reporting a side effect: the Yellow Card scheme
The MHRA monitors every vaccine used in the UK for side effects. Anyone can report a suspected side effect through the Yellow Card scheme, online or in the Yellow Card app. It doesn’t replace medical advice: speak to a GP, pharmacist or 111 if you’re worried.
When to call 111 or see a GP
Speak to a GP or pharmacist, or call 111, if side effects are getting worse or haven’t settled after a few days, you feel very unwell or short of breath, or you’re worried about your own or your child’s reaction. Tell a doctor straight away if the arm you had the jab in becomes very swollen. Call 999 for signs of a severe allergic reaction, chest pain or severe difficulty breathing.
Vaccines aside, the winter basics still matter: sleep, daily movement, regular meals and, as the NHS advises, considering 10 micrograms of vitamin D a day in autumn and winter. See vitamin D in winter, supporting your immune system, sleeping with a cold and winter wellness.
FAQs
Are there any side effects to this year’s flu jab?
Yes, the usual mild ones: a sore arm, tiredness, a headache, aching muscles and a slight temperature. The NHS says they get better within 1 to 2 days.
Can the flu jab make you tired the next day?
Yes. Feeling tired the day after is common and usually passes within 1 to 2 days. Rest and drink plenty of fluids.
How long do flu jab side effects last?
Usually 1 to 2 days. Speak to a GP or pharmacist, or call 111, if they get worse or don’t settle.
Can I have the flu and COVID jabs together?
Yes. The NHS says you can have them at the same time; they are usually given in different arms. You may feel a little more tired or achy for a day or two.
Can the flu jab give you flu?
No. The injected flu vaccines used in the UK don’t contain live flu viruses, so they can’t give you flu.
Why do I feel ill a week after my flu jab?
Common side effects pass within a few days, so feeling ill a week later is more likely to be a cold, COVID-19 or flu caught before the vaccine started working. See a GP or call 111 if you’re worried.
Sources
- NHS. Flu vaccine (reviewed 29 September 2026).
- NHS. Children’s flu vaccine.
- UKHSA. Influenza: the Green Book, chapter 19 (25 August 2026).
- UKHSA, NHS England and DHSC. National flu immunisation programme 2026 to 2027 letter.
- NHS. COVID-19 vaccine.
- NHS. Why vaccination is important and vaccination tips for parents.
- NHS. Flu and anaphylaxis.
- emc patient leaflets: Cell-based Trivalent Influenza Vaccine Seqirus and Efluelda TIV-HD.
- MHRA. Yellow Card scheme.
This guide is general information, not medical advice. Follow the advice of the person who vaccinates you and the leaflet for your vaccine. Evopure doesn’t make or sell vaccines, and this article doesn’t feature any Evopure products.
