Eat a meal and hydrate well

Have a substantial meal and drink at least two large glasses of water in the hours before your vaccination appointment. This is the single most effective step to reduce the risk of a vasovagal reaction, which is the medical term for feeling faint after an injection. Vasovagal reactions are nervous system responses to the injection and are not allergic reactions. They are much more likely on an empty stomach or when dehydrated. Low blood sugar and dehydration both lower the threshold for this response.

Wear appropriate clothing

Wear a loose-fitting top or a short-sleeved top that can be easily rolled up to expose the upper arm. The vast majority of adult vaccines are given as intramuscular injections into the deltoid muscle of the upper arm. If you cannot comfortably expose either upper arm due to clothing, the vaccinator can use the thigh instead for some vaccines, but this requires notification in advance or at check-in.

Know and report your medical history

Be ready to tell the vaccinator about any allergies (particularly to previous vaccines or vaccine components such as eggs, gelatine, or antibiotics), any previous severe reaction to a vaccine, any medications you are currently taking, whether you are pregnant or breastfeeding, and whether you have recently received another vaccine. This information is gathered as part of the standard pre-vaccination health assessment and is essential for safe practice.

Check whether you feel well

If you have developed a fever or feel significantly unwell in the days before your appointment, contact the vaccination centre to discuss whether to attend. A mild cold without fever is generally not a reason to postpone. Fever above 37.5 degrees Celsius is a reason to postpone until you have recovered. See our full guide on vaccinating when ill for more detail.

Bring relevant documents

If you have a personal vaccination record, NHS vaccination history printout, or travel vaccination certificate relevant to the appointment, bring it. This allows the vaccinator to confirm what you have previously received and update your records accurately. For travel vaccinations in particular, knowing your full vaccination history can determine whether booster doses are needed.

The pre-vaccination check

When you arrive, a vaccinator will verify your identity and complete a brief health questionnaire. This takes two to five minutes and covers allergies, current illness, medications, pregnancy status, and recent vaccinations. It is routine but important. The vaccinator uses this information to confirm the vaccine is appropriate and safe for you on that particular day.

The injection itself

The vaccination is administered in seconds. The vaccinator will ask you to expose your upper arm, will clean the skin with an alcohol swab and wait for it to dry, and will inject the vaccine using a fine-gauge needle. The needle is in the skin for less than a second. Most people describe the sensation as a brief sharp sting at insertion, followed by a dull pressure as the vaccine is administered, followed by mild aching in the arm that typically develops over the next hour.

Relaxing the muscle

The most effective thing you can do during the injection is keep your arm muscle as relaxed as possible. A tensed muscle creates more resistance to needle entry and increases the sensation of insertion. Letting your arm hang loosely or resting it on your lap with no tension in the shoulder helps. Looking away if the sight of needles causes anxiety is entirely appropriate and makes the experience more comfortable for most people.

The post-vaccination wait

Many vaccination programmes ask you to remain at the venue for 15 minutes after the injection. This observation period allows trained staff to be present if you develop an immediate adverse reaction. Anaphylaxis, which is a severe allergic reaction, is the rare immediate risk that this period is designed to manage. It is very rare but occurs within minutes of injection when it does occur. Use the time to sit comfortably, have a drink of water, and move your arm gently.