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Reactions to vaccines
Vaccines are effective and safe; however, side effects sometimes occur. These are usually mild reactions and are part of the normal immune response to vaccination. Serious reactions to vaccination, such as anaphylaxis, are extremely rare.
Common mild vaccine reactions
Common adverse events following immunisation (AEFI) are usually mild and temporary. These reactions generally occur within a day or two of immunisation and are transient. Live virus vaccines (e.g., MMR, yellow fever and varicella) can occasionally cause symptoms such as fever, headache, tiredness and/or rash. These may be delayed until several days after vaccination.
Uncommon, severe adverse reactions
Although they can be severe, most rare vaccine reactions occur soon after immunisation, are self-limiting, and rarely lead to long-term complications. Anaphylaxis, for example, although potentially life-threatening, is quickly and very effectively treated and has no long-term effects. Other rare reactions include Guillian-Barre syndrome (GBS), which affects the nervous system, or other autoimmune disorders. It is important to emphasise that these adverse reactions are extremely rare and that the benefits of vaccination usually far outweigh the risks.
After vaccination, it is very important to stay at the clinic for 10–15 minutes of observation.
If you have any concerns about the safety or effectiveness of vaccines, please feel free to discuss this with one of our doctors.
What are the likely side effects?
The side effects of vaccination can vary depending on the specific vaccine and the individual receiving it. However, there are no restrictions on normal activities; most people can work, drive a car, play sports or go to the gym. Nevertheless, it is better to take it easy if you are experiencing any side effects.
Sore or red arm
The most common side effects following vaccination are soreness, redness and swelling at the injection site. If you use your arm normally after a vaccination, it will help ease the soreness. In some people, vaccines may cause a lump or hardness at the injection site that persists for a few weeks. If your arm is red, hot and/or sore, place an ice pack over the affected area. You can take paracetamol. Intradermal vaccines (e.g., rabies) may cause itchiness at the injection site and a small surface lump, which may persist for a few weeks. This is all part of a normal immune response to vaccination.
Fevers and feeling unwell
Live virus vaccines such as yellow fever, varicella (chickenpox) and MMR (measles, mumps, and rubella) may cause a fever, headache, tiredness and muscle aches. Up to 25% of yellow fever vaccine recipients reported mild adverse events. Symptoms usually appear in the first five days after vaccination and can last up to two weeks. With MMR vaccinations, up to 15% of MMR vaccine recipients develop a high fever (>39.4°C).
Most vaccines used today contain killed organisms or fragments of organisms and cannot cause the illness they are used to prevent. A good example is the flu vaccine, which cannot cause the flu. However, some people react more strongly to vaccines and may feel unwell afterwards. If you develop a fever or become unwell after vaccination, please call our clinic and speak to one of our doctors or nurses, or contact your nearest hospital.
Allergic reactions (anaphylaxis)
Allergic reactions are rare but may be very serious. After vaccination, notify one of our staff members immediately if you feel:
- warm or itchy, or develop a rash
- faint (especially on standing up) or dizzy
- shortness of breath, or start to wheeze or cough
- your throat, face, hands or limbs begin to swell
- nausea or stomach pain
- suddenly tired.
Symptoms usually develop within 15 minutes of vaccination, hence the need to wait in the clinic after vaccination. Occasionally, allergic symptoms can occur several days later. If you develop one or more of the above symptoms after leaving the clinic, seek medical help immediately. People with severe allergies to eggs may not be able to be immunised against yellow fever, flu and MMR. Travellers with a penicillin allergy, however, can be vaccinated safely.
Can I drink alcohol after vaccines?
If you are taking typhoid capsules, alcohol (and food) must not be taken within a few hours of each capsule. However, it is okay to have alcohol after other vaccinations.
There is no evidence that drinking in moderation is harmful after most vaccinations.
In general, there are several reasons to avoid excess alcohol consumption after a vaccination. Excess alcohol consumption can potentially mask the side effects of the vaccine and make it difficult to determine which side effects are attributable to the vaccine or alcohol.
Excessive alcohol consumption on a regular basis may also affect your immune system. Research has shown that an alcohol intake of 15 or more drinks per week for men and eight for women may suppress the immune system, along with other factors such as smoking, a lack of sleep and a poor diet.
If you do decide to drink following a vaccine, you should attempt to drink in moderation. If you are concerned about this, you should contact the doctor or nurse administering the vaccine to confirm the safety of alcohol intake following an upcoming vaccine.
Fainting
If you have a history of fainting after injections, make sure you tell the doctor. You may be asked to lie down during vaccination and for a while afterwards so that we can be sure you are feeling well before you leave the clinic.
What if I have a cold?
It is medically safe to be vaccinated if you have a runny nose, sore throat or cough. You should delay vaccination if you have a fever over 39°C or are sick enough to have to stay in bed.
Will vaccines weaken my immune system?
There is no evidence that vaccination weakens the immune system. In fact, vaccination is a very effective way of strengthening the immune system’s response to diseases. However, to avoid the risk of unnecessary side effects, vaccinations should only be recommended when there is a significant risk of disease.
How do I manage common vaccine side effects?
Many types of vaccines have similar mild side effects that can be managed at home. Common side effects include localised pain, swelling or redness at the injection site, fatigue, muscle or joint pain, weakness, mild fever, or chills.
These side effects indicate that your body is building immunity against the disease. To manage these side effects, over-the-counter painkillers and fever reducers such as paracetamol or ibuprofen can be taken.
Plenty of rest and hydration are recommended following a vaccine. Most side effects should last no longer than two days. If they last longer, contact your medical provider.
Serious reactions to vaccines are extremely rare. If you experience a life-threatening allergic reaction, such as swelling in the face, lips, tongue, or throat, difficulties breathing or hives, get immediate emergency medical assistance.
What are the side effects of the flu vaccine?
Like any medical product or medicine, the flu vaccine can cause side effects. Common side effects include redness, warmth or swelling at the site of the injection, headaches, tiredness or body aches. Over-the-counter pain relievers such as ibuprofen or paracetamol can be used to reduce these symptoms.
Rarely, fainting or dizziness may be experienced. This can be relieved by resting during and after receiving the flu vaccine. A mild fever is also a rare side effect that can be relieved by taking paracetamol or ibuprofen.
Side effects should not last any longer than two days. Contact the doctor or nurse who is administering the vaccine if you are concerned about post-flu shot side effects.
Importantly, as the flu vaccine is not a live vaccine, it cannot give you the flu.
What are the side effects of the typhoid vaccine?
The typhoid vaccine is used to prevent typhoid fever, a serious and potentially life-threatening illness caused by Salmonella typhi bacteria. The vaccine is widely considered to be safe and effective at preventing this illness. However, a range of side effects may be experienced following the vaccine.
Two types of typhoid vaccines are available: a live, attenuated (weakened) oral vaccine and an inactivated (killed) vaccine in the form of an injection.
Side effects of the injection typically include swelling, redness or pain at the injection spot, headaches, fever and general discomfort. These side effects can be alleviated through rest, over-the-counter pain medications, and hydration.
The oral typhoid vaccine (capsules) may cause mild to moderate side effects such as nausea, vomiting, stomach cramps, diarrhoea and a rash within 12–24 hours after taking each capsule. Oral typhoid vaccine side effects can be minimised through hydration and rest. If these side effects become severe, contact a medical provider.
Side effects from both typhoid vaccines should not last for more than two days after receiving them. As with any vaccine or medication, there is a very small risk of developing a serious reaction. These serious adverse reactions are extremely rare, and the benefits of vaccination usually far outweigh the risks.
Should I exercise after getting a vaccination?
Generally, it is safe to exercise after vaccinations. However, it may be prudent to avoid very strenuous exercise for a couple of hours after a vaccination. You may experience side effects that could inhibit your usual workout intensity, such as local tenderness. If you develop other side effects such as fatigue or body aches in the days after vaccination, this may also reduce your capacity to exercise. If this does occur, try a lighter exercise than usual and make sure to listen to your body.
How long do vaccinations last?
The list below outlines the usual duration of protection once the vaccination course is complete. For some vaccines, the duration of protection is uncertain.
- Chickenpox: long-term
- Cholera (oral): up to 2 years
- Diphtheria: 10 years
- Flu vaccine: up to 1 year
- Hepatitis A: probable lifetime protection
- Hepatitis B: lifetime
- Japanese encephalitis (JE): the duration of protection will depend on the type of
- vaccination received
- Measles, mumps and rubella: lifetime
- Meningitis: new conjugate vaccines give up to 5 years of protection
- Pneumonia: >5 years, probably lifetime
- Polio booster: lifetime
- Rabies (pre-exposure): immune memory persists for life; booster doses are required
- in certain instances
- Tetanus: 5–10 years
- Typhoid (injection): up to 3 years
- Typhoid capsules x 3: 3 years
- Typhoid capsules x 4: 5 years
- Whooping cough: immunity begins to wane after 3–5 years
- Yellow fever: long-term; certificate valid for life