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Not an emergency service. If you or someone else is seriously unwell — for example chest pain, breathing difficulty, heavy bleeding or collapse — call 999. For urgent advice when it is not life-threatening, call NHS 111.

Recovery & Aftercare Guide

Hay fever injection

A seasonal injection given after assessment. Minimal aftercare, with a short observation period.

Important. Your individual instructions from your treating clinician take precedence over this general information. If anything here differs from what your clinician has told you, follow your clinician’s advice and contact the hospital if you are unsure.

Overview

The hay fever injection is given after assessment, when other treatments have not adequately controlled symptoms.

The appointment includes a discussion of benefits and risks, the injection itself, and a short observation period.

Before your procedure

  • Attend the consultation. This treatment is only given after assessment and is not suitable for everyone.
  • Tell the team about all medicines and any long-term conditions, particularly diabetes, high blood pressure, glaucoma, stomach ulcers or mental health conditions.
  • Tell the team if you have any current infection.
  • Tell the team if you are pregnant, breastfeeding or trying to conceive.
  • Wear a top with a sleeve that rolls up easily.
  • Eat and drink normally.

Aftercare

Observation

You will usually be asked to remain in the clinic for a short period after the injection.

Injection site

Aching at the site for a day or two is common.

Onset

Effect usually begins within a few days.

Activity

No restrictions, though you may prefer to avoid heavy use of that arm the same day.

Blood glucose

If you have diabetes, monitor your blood glucose more closely for several days, as levels may rise temporarily.

Follow-up

Contact the clinic if symptoms are not controlled, rather than seeking a repeat injection elsewhere without review.

Red flags — when to seek help

These lists are not exhaustive. Trust your judgement and seek advice if you are worried.

Emergency Call 999 or go to your nearest emergency department

  • Difficulty breathing, throat or facial swelling, or a widespread rash shortly after the injection
  • Feeling faint with a rapid heartbeat shortly after the injection

Contact us Contact the hospital, or call NHS 111 out of hours

  • Spreading redness, heat or swelling at the injection site after 48 hours
  • Mood changes, marked sleep disturbance or unusual agitation in the days afterwards
  • Blood glucose that is difficult to control if you have diabetes
  • Skin thinning or a dent developing at the injection site

Tower Bridge Hospital, 97–99 Whitechapel Road, London E1 1DT. Telephone 020 7916 0029. If in doubt and the situation is not life-threatening, call NHS 111.

Frequently asked questions

How long does it last?

The effect is intended to cover part of the pollen season. Your clinician will discuss what to expect.

Why do I need to stay after the injection?

A short observation period allows any immediate reaction to be identified and managed.

Is it suitable for everyone?

No. It is not appropriate for some conditions, which is why assessment comes first.

Can I have it every year?

This is a clinical decision reviewed each season, not an automatic repeat.

More information

Clinical reviewer
Dr Haydar Bolat, Clinical Director
Review date
21 July 2026
Review by
21 July 2027
Version
1.0
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