A trip abroad often means ticking off a checklist of jabs, and for many travellers Hepatitis A and Hepatitis B vaccinations are near the top of that list. Once the injection is done, it is natural to wonder what the next day or so might bring, particularly if this is your first time having either vaccine.
Most reactions are mild and settle on their own, but knowing what is typical in the first 24 hours can help you feel more prepared and less anxious about the process. This guide walks through what to expect, what is considered normal, and when it may be worth seeking advice.
If you are planning travel from Pembroke and want to discuss vaccinations ahead of your trip, contact us at Mendus Pharmacy or visit our travel services page to see how we can help.
Quick Answer
In the first 24 hours after a Hepatitis A or Hepatitis B vaccine, the most common reactions are soreness, redness or swelling at the injection site, along with mild tiredness or a headache. These effects are usually mild, appear within a few hours, and tend to ease within a day or two without treatment. Fever and more noticeable side effects are less common but can happen, and it is worth knowing the difference between an expected reaction and something that needs medical attention.
What Is in the Hepatitis A and B Vaccine?
Hepatitis A and Hepatitis B vaccines protect against two different viruses that both affect the liver, but they spread in different ways. Hepatitis A is usually linked to contaminated food or water, while Hepatitis B spreads through blood and certain bodily fluids. Depending on your travel plans and health history, you may be offered the vaccines separately or as a combined injection that covers both in one dose.
Both vaccines work by prompting the immune system to build protection, which is why some mild, short-lived reactions in the first day or so are a normal part of the process rather than a sign of anything going wrong.
Common Side Effects in the First 24 Hours
According to the NHS, injection site reactions are the most frequently reported side effect of the hepatitis vaccines, and these typically appear within the first few hours. Common effects reported in the first 24 hours include:
- Soreness, redness or a small lump at the injection site
- Mild swelling around the area where the injection was given
- Tiredness or feeling generally run down
- Headache
- Mild muscle aches, particularly in the arm used for the injection
- A slightly raised temperature
These reactions are part of the immune system responding to the vaccine and are generally considered a normal, expected part of the process rather than a cause for concern.
Typical Timeline of Reactions
| Timeframe | What You Might Notice |
|---|---|
| 0 to 4 hours | Soreness or tenderness at the injection site begins to develop |
| 4 to 12 hours | Redness, mild swelling, tiredness or a mild headache may become more noticeable |
| 12 to 24 hours | Symptoms are usually at their most noticeable before starting to settle |
| 24 to 48 hours | Most mild reactions begin to ease and gradually resolve |
Less Common Side Effects to Be Aware Of
Some reactions are reported less frequently but are still worth knowing about. These can include:
- Nausea or a mild upset stomach
- Joint aches beyond the injection site
- Dizziness or feeling lightheaded shortly after the injection
- A more pronounced fever than a slightly raised temperature
- Loss of appetite for a short period
Serious allergic reactions to vaccines are rare, which is one reason vaccinations are given by trained healthcare professionals who can monitor you for a short period afterwards.
Hepatitis A vs Hepatitis B: Side Effect Comparison
| Factor | Hepatitis A Vaccine | Hepatitis B Vaccine |
|---|---|---|
| Most common reaction | Soreness at injection site | Soreness at injection site |
| Onset of reactions | Usually within hours of injection | Usually within hours of injection |
| Typical duration | One to two days | One to two days |
| Given as combined dose | Yes, can be combined with Hepatitis B | Yes, can be combined with Hepatitis A |
Tips for Managing Side Effects at Home
Gently moving your arm as normal and applying a cool, clean compress to the injection site can help ease discomfort. Avoid rubbing or pressing firmly on the area.
Resting, staying hydrated and dressing lightly can help if you feel warm or have a mild headache. Speak to your pharmacist if you are unsure which over the counter remedies are suitable for you.
Tiredness is common in the first day, so it can help to plan lighter activities on the day of your vaccination rather than anything strenuous.
Drinking water throughout the day can help your body recover and may ease mild symptoms such as headache or tiredness.
When to Contact a Healthcare Professional
Most reactions settle without any intervention, but it is sensible to seek advice if you notice:
- Swelling, redness or pain that gets worse rather than better after a day or two
- A high temperature that does not settle
- Symptoms of an allergic reaction, such as difficulty breathing, swelling of the face or throat, or a widespread rash
- Any symptom that feels severe or is causing you significant concern
If you experience a serious reaction shortly after vaccination, seek emergency medical help immediately.
Everyone’s Reaction Is a Little Different
It is worth remembering that not everyone experiences side effects, and some people notice very little beyond mild soreness at the injection site. Factors such as previous vaccine history, general health, and even which arm the injection is given in can all play a small part in how your body responds.
If you have concerns before your vaccination, particularly around allergies, current medication or existing health conditions, it is always worth discussing this with a healthcare professional beforehand.
Frequently Asked Questions
Taking painkillers before vaccination as a precaution is not generally recommended, as it is not proven to reduce side effects and may affect the immune response. Speak to your pharmacist if you have concerns.
Mild warmth around the injection site alongside redness or swelling can be part of a normal local reaction. If the warmth spreads significantly or is accompanied by increasing pain, seek advice.
Light activity is usually fine, but many people prefer to take it easier for a day if they feel tired or have arm soreness. Listen to how your body feels rather than pushing through discomfort.
Having both vaccines together, or a combined dose, does not typically cause significantly worse side effects than having them separately, though this can vary between individuals.
Since most reactions settle within one to two days, having the vaccine a few days to a couple of weeks before departure allows time to recover, alongside building adequate protection before you travel.
Children can experience similar reactions such as soreness and mild fever, though dosing and monitoring may differ. A healthcare professional can advise on what to expect for a child’s specific vaccination.
Mild side effects can reflect the immune system responding to the vaccine, but their absence does not mean the vaccine has not worked. Protection develops regardless of whether noticeable side effects occur.
Planning Travel Vaccinations in Pembroke
Understanding what to expect in the first 24 hours can make the whole process feel far less daunting, especially if you are having travel vaccinations for the first time. Our team can talk you through your individual travel plans, any relevant health history, and what vaccinations may be recommended well ahead of your trip.
Get in touch with Mendus Pharmacy to discuss your travel vaccination needs, or explore our travel services and vaccinations pages to find out more, or read more on our blog for further travel health guidance.