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COVID Vaccine Side Effect Guidance

Let's cover normal side effects and how to minimize the discomfort following a COVID-19 vaccine or booster.

Kinsa’s Nurse Blake here with some tips to soothe any side effects you or your kiddo might be experiencing from a recent COVID-19 vaccine/booster. If we haven’t met before, hello! I write all of Kinsa’s clinical guidance, with the help of our team of doctors and epidemiologists.

If you or your child are experiencing a mild to moderate fever from the vaccine, please know this is totally normal. If your child isn't experiencing much discomfort from the fever, there’s no need to treat it with over-the-counter fever reducers. Encourage them to rest, hydrate and take off a couple layers.

If their fever is really bugging them, give them Tylenol (acetaminophen) instead of Motrin (ibuprofen). Small studies suggest that Tylenol will interfere less with the immunity boost conferred by their vaccine.

Treating Common COVID-19 Vaccine Side Effects

  • Sore arm at the injection site: non-intuitively, encourage them to exercise it or move it around! Ice or a cool, wet towel can also soothe.
  • Headache: hydrate and again, if you need to give medication, give Tylenol.
  • Fever-associated symptoms like muscle aches and fatigue: hydrate, rest and treat them to a warm bath with epsom salt.


A Couple Less Common Side Effects...

Despite these both being less common, they're also normal and a sign that your child's immune system is having the desired reaction to the vaccine.

  • Swollen lymph nodes: if you feel hard, tender round lumps in your child's neck, under their chin, in their armpits or around their groin within a week of getting their vaccine, say hello to their lymph nodes. Clusters of immune cells live inside these guys, so the fact that they’re reacting to the vaccine by swelling slightly is promising! I get it, mystery lumps in the body = terrifying. Know they’ll resolve with time. In the meantime, dip a towel in hot water, wait for it to cool and gently press it against any swollen lymph nodes you notice.
  • A rash that appears around the injection site a full week after the immunization (“COVID arm”): while most side effects appear within 1-3 days of receiving the vaccine, this big itchy, red blotch can be a jarring one that appears a week after the shot. Similarly to treating day-of injection pain, hold a cool, wet compress against the rash or try ice. The rash should subside within a few days.

Regardless of what side effects your child is experiencing, good news: they should subside within 3 days of receiving the vaccine or booster.

Hang in there!