Cortisone injections are commonly used to treat inflammation and pain associated with various conditions like arthritis, tendinitis, bursitis, and others. While cortisone shots are generally safe and effective, some side effects can occur after receiving the injection. One of the potential side effects is feeling sick or having flu-like symptoms for a few days after the shot.
What is a cortisone injection?
A cortisone injection delivers a synthetic version of the cortisol hormone directly into the affected area. Cortisol is a steroid hormone naturally made by the adrenal glands that has important functions in the body, including regulating inflammation.
Injecting cortisone can rapidly reduce inflammation, swelling, and pain associated with inflammatory conditions. Some common conditions cortisone injections are used to treat include:
- Arthritis – injections given into joints
- Tendinitis – injections given around tendons
- Bursitis – injections given into bursa sacs
- Carpal tunnel syndrome – injections given into the wrist
- Trigger finger – injections given into the affected finger
- Plantar fasciitis – injections given into the foot
- Back pain – injections given around spinal nerves
The medication typically starts working within 24-48 hours to relieve pain and inflammation at the site. The effects can last for several weeks or months depending on the condition being treated.
How do cortisone injections work?
Cortisone shots work by delivering a high dose of steroid medication directly to the inflamed area. The corticosteroid mimics the effects of the natural hormone cortisol, which regulates the body’s immune response and helps reduce inflammation.
Specifically, cortisone works by:
- Suppressing the immune system to block release of inflammatory chemicals
- Reducing swelling by constricting blood vessels
- Blocking transmission of pain signals
This leads to a rapid easing of the inflammatory symptoms causing pain and swelling, though the effects are temporary.
What are the side effects of cortisone injections?
Cortisone injections are generally well-tolerated, however some temporary side effects can occur. Potential side effects include:
- Increased pain or flare up of inflammation for 1-2 days after the shot
- Skin changes like bleeding, discoloration, thinning, or tiny indentations at the injection site
- Nerve injury from the needle (rare)
- Infection at the injection site
- Tendon weakening or rupture (rare with appropriate treatment)
- Elevated blood sugar levels for a few days
- Facial flushing for 1-2 days
- Headache
- Feeling sick or flu-like symptoms
The sickness or flu-like symptoms some people experience are due to the way corticosteroids suppress the immune system. Let’s discuss this side effect next.
Can you feel sick after a cortisone injection?
It is not uncommon to experience some body aches, low fever, fatigue, nausea, or generally feeling unwell for a day or two after receiving a cortisone injection. This occurs because corticosteroids suppress the immune system, which can temporarily make people more vulnerable to viruses or make any existing infection feel worse.
Some statistics on how many people feel sick after cortisone injections:
- 10-25% of patients report flu-like symptoms within 2 days of the shot
- Fatigue is the most commonly reported symptom (up to 20% of patients)
- About 5-15% of patients experience nausea or vomiting
- Fever occurs in around 2-10% of patients
- Body aches and headaches are also fairly common
These cortisone flu symptoms are usually mild and resolve within 48 hours after the injection. More severe reactions are possible but very rare. Seeking prompt medical attention is recommended if you experience symptoms like high fever, severe muscle weakness, or confusion after the shot.
Why does this happen?
There are a few reasons why corticosteroid shots can make some people feel sick:
- The high dose of steroid suppresses the immune system, making people more vulnerable to viruses and bacteria.
- Cortisone may reactivate a latent infection or make current infections feel worse.
- Sudden changes in cortisol levels can temporarily disrupt hormone balance.
- Some people may have an allergic-type reaction to components in the injection.
For most people, the immune suppression and hormone effects are temporary and resolve once the medication starts wearing off. But people are often advised to take it easy after a cortisone shot and watch for concerning symptoms, especially with frequent injections.
Risk factors
Certain people appear more prone to developing flu-like side effects after cortisone injections. Risk factors include:
- Older age – older adults seem more likely to experience symptoms due to weaker immunity.
- High cortisone dose – higher doses suppress immunity more.
- Frequent injections – repeat shots cause greater cumulative immune suppression.
- Diabetes – corticosteroids can increase blood sugar variability.
- Existing infection – active infections worsen with immune suppression.
- Past reactions – those who reacted before are likely to react again.
Younger, healthier people who receive occasional low-dose injections are least likely to develop symptoms. Talk to your doctor if you are concerned about possible reactions.
Preventing flu-like symptoms
While some temporary sickness is hard to prevent completely after cortisone injections, the following precautions may help reduce the chances of developing flu-like side effects:
- Avoiding strenuous exercise for 2-3 days after the shot to let your immune system recover.
- Staying well hydrated and eating a healthy diet.
- Getting plenty of rest after the injection.
- Washing hands frequently and avoiding sick contacts to prevent infection.
- Treating any existing infections before getting the shot.
- Discussing any past reactions with your provider.
- Asking for the lowest effective cortisone dose.
- Spreading out frequency of injections when possible.
Being aware this can occur and not overexerting yourself after the shot are probably the most effective precautions. Call your doctor if you have severe, persistent, or worsening symptoms after an injection.
Treatment
Mild flu-like discomfort often resolves on its own within a couple days after a cortisone injection. Some tips for relieving symptoms:
- Resting and taking it easy on activity for 2-3 days.
- Acetaminophen or ibuprofen for fever and body aches.
- Drinking plenty of fluids.
- Eating light, easily digested foods.
- Applying cool compresses to the forehead for fever.
Seek medical advice if you experience severe symptoms like high fever over 102°F, intolerable headaches, excessive vomiting/diarrhea leading to dehydration, severe muscle weakness, dizziness, or confusion after an injection. You may need hydration, medications, or testing to assess for infection.
Rarely, symptoms may represent an acute adrenal crisis if both adrenal glands stop functioning due to chronic steroid use. This is a medical emergency requiring prompt treatment with IV steroids.
When to call your doctor
Contact your doctor right away if you have any of the following after a cortisone injection:
- High fever over 102°F
- Flu symptoms that last over 2 days or seem to worsen
- Severe muscle weakness or severe joint/muscle pain
- Dizziness, confusion, or fainting
- Difficulty breathing or chest pain
- Uncontrolled vomiting or diarrhea
- Sudden severe pain or swelling at the injection site
- Signs of infection like pus/discharge, increasing redness or heat
- Rash over body, itching, swelling, or shortness of breath (may indicate allergic reaction)
Routine side effects like low fever, malaise, and mild headaches can usually be managed with rest and over-the-counter medications. But more concerning reactions may need medical treatment. Being attentive to your symptoms and contacting your doctor with any severe or worsening issues is advised.
Long term risks
While temporary sickness is common after single cortisone injections, long-term immunosuppression can occur after frequent, repeated injections over time. Potential long term risks include:
- Increased susceptibility to infections
- Difficulty recovering from illnesses
- Slower wound healing
- Acne and skin changes
- Cushing’s syndrome (from excess cortisol)
- Adrenal insufficiency
- Osteoporosis
- Stomach ulcers
- Mood changes like depression or irritability
- Diabetes onset or destabilization
- Cataracts and eye problems
That’s why doctors try to avoid overusing injections and limit them to 3-4 per year per site when possible. Patients on chronic steroid therapy may need calcium and vitamin D supplementation to counteract bone loss. Discuss the benefits and risks of repeated cortisone shots with your provider.
Conclusion
It’s fairly common to experience temporary flu-like discomfort, body aches, fever, nausea, fatigue, or generally feeling unwell for a day or two after receiving a cortisone injection. This occurs because corticosteroids suppress the immune system, making people more prone to infection and viruses.
Symptoms are usually mild and go away within 48 hours. Rest, hydration, light diet, and over-the-counter medications can help manage routine side effects. Call your doctor if you have severe, worsening, or prolonged symptoms after the shot. Long-term immune suppression is also a concern with frequent, repeated injections over time. Discuss the pros and cons of cortisone shots with your provider.