Psoriatic Arthritis Flare or Infection? How They’re Different (Symptoms and Pictures)
Key takeaways:
Psoriatic arthritis (PsA) flares and infections can cause the same symptoms — like fatigue, joint pain, and rashes.
Infection can cause these symptoms, or it can trigger a PsA flare. It can be tough to tell the difference.
If you’re worried about either a PsA flare or infection, talk to a healthcare professional to figure out a plan.
Table of contents
Psoriatic arthritis (PsA) is an autoimmune condition that can lead to joint pain, rashes, and fatigue. Although it's a lifelong condition, the symptoms tend to wax and wane. But when your symptoms worsen, it’s important to figure out what’s going on. You could be having a PsA flare, or you may be experiencing symptoms of an infection.
Certain PsA treatments can increase your risk of infection. And some infections can cause symptoms that mimic PsA flares. Here, we walk through PsA flares, infections, and what to do if you suspect either.
What is a psoriatic arthritis flare?
A PsA flare is a temporary worsening of symptoms. PsA flares are different for everybody. When your PsA flares, symptoms you’ve had before — like rashes and joint pain or swelling — typically happen again. In severe cases, a new symptom might also show up.
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Some typical PsA flare symptoms include:
Joint pain or swelling
Psoriasis rashes — in new areas or areas where you’ve had rashes before
Pain at the site where tendons attach to bone, like the back of the heel (enthesitis)
Swelling of an entire finger or toe, also called “sausage digit” (dactylitis)
Back pain and stiffness due inflammation of the spine or sacroiliac joints (spondylitis and sacroiliitis)
Fatigue
Fever
Some of these symptoms can also show up from various infections. Determining whether your symptoms are caused by a PsA flare or infection is key to treatment.
Pictures of psoriatic arthritis flares
Here are some pictures of a PsA rash flare in different locations and skin tones.
What triggers psoriatic arthritis flares?
PsA symptoms can be different from person to person, and triggers can also vary. Here are some common ones:
Not taking your medications
Stress
Lack of sleep
Weather changes
Infections (bacterial and viral, for example)
Smoking
Why are people with psoriatic arthritis at increased risk of infections?
People with PsA are at increased risk of infections for two main reasons:
Psoriasis rashes
Immunosuppressive medications
You may wonder if a certain diet can help prevent psoriatic arthritis (PsA) flares. Fad diets aren’t recommended, but some foods may help prevent inflammation.
Triggers can vary from person to person. Read how one person with PsA manages her flares and prioritizes self-care.
Septic arthritis is a medical emergency. It’s important to know who’s at risk and how to spot a joint infection.
Psoriasis rashes can leave skin open and raw. Rashes can be itchy, and it can be hard not to scratch! But this can cause breaks in the skin, which allows germs to make their way into the skin. This could cause a skin infection (cellulitis) or a deeper infection (more on this below).
People with PsA typically take immunosuppressive medications to stop the immune system attack on their skin and joints. For example, you might be taking methotrexate or a biologic medication like Enbrel. These medications turn off one piece of your immune system in order to help control the condition. But at the same time, it can be easier for you to get infections while taking them. You could also get sicker than normal from an infection.
Symptoms of infection
As mentioned above, the problem is that sometimes infection symptoms are similar to those of a PsA flare. For example, viral infections due to influenza or SARS-CoV-2 can cause flu-like symptoms such as:
Fever
Fatigue
Headache
Infections can also worsen joint pain and swelling due to PsA.
What happens if a person with psoriatic arthritis gets an infection?
When a person with PsA gets an infection, three things could happen:
Nothing major: You get sick. Your immune system fights the infection. You get better. Your PsA feels fine.
PsA flare: You get sick. Your immune system wakes up to fight the infection. And, in the process, your PsA also wakes up a bit. Your PsA symptoms get worse because the infection triggers a PsA flare. The flare may need a short course of anti-inflammatory medications — like steroids or nonsteroidal anti-inflammatory drugs (NSAIDs) — to calm it down.
Joint pain and swelling: Some infections can cause joint pain and swelling that look like a PsA flare. But it isn’t actually a flare. Certain viral and bacterial infections target the joints more than others and cause joint pain. Other symptoms — such as fever or rashes (that are different from your psoriasis rashes) — may also occur.
What is septic arthritis?
Septic arthritis is when a joint gets infected with bacteria or a rare kind of germ. Germs may enter the joint directly from a cut, puncture wound, or injury near the joint. And if you have a bloodstream infection, the infection may also spread to the joint via the bloodstream.
Septic arthritis is very dangerous and requires hospitalization. To diagnose septic arthritis, a healthcare professional will remove fluid from the joint with a needle (called “arthrocentesis”). Then a specialist examines the fluid under the microscope for abnormal cells and bacteria. In some cases, blood tests or imaging tests may be helpful.
Symptoms of septic arthritis include:
Fever
Redness, swelling, and extreme pain in one joint (rarely more)
Inability to bear weight on the joint
“Micro-motion tenderness,” when even moving the joint a millimeter causes severe pain
If you’re concerned about septic arthritis, call your rheumatologist or primary care provider as soon as possible.
How do you tell the difference between a psoriatic arthritis flare and infection?
This can be tricky, even for healthcare professionals. Sometimes, other symptoms can point you to an infection, like sore throat or cough, since you wouldn’t expect these with a PsA flare.
The best thing to do is call your rheumatologist to discuss the next steps. They’ll ask you questions and possibly order tests. You also might need to go in for an evaluation. In general, it’s better to err on the side of caution and get medical attention, since untreated infection can have severe consequences.
Treatment for psoriatic arthritis flares and infections
Treating a PsA flare involves a few different steps. It’s important to contact your rheumatologist to see if any changes to your medication(s) could help. Then focus on self-care:
Make sure you’re getting plenty of sleep
Decrease stressors as much as possible
Avoid aggravating activities
Last but not least, don’t forget to take your medications.
If your rheumatologist is worried about septic arthritis, they’ll send you to the emergency room. Treatment includes antibiotics, by mouth and/or intravenous (IV), for at least a couple of weeks. Sometimes, surgery to “wash out” the infected joint is needed.
Frequently asked questions
PsA flares usually last a couple of days to a week. But if you’re not sure if you’re experiencing a flare or an infection, it’s best to call your rheumatologist. Don’t wait to see if your symptoms go away on their own.
There isn’t a “best” medication, or even a one-size-fits-all treatment plan, for everyone with PsA. What’s best for you can depend on things like your symptoms, other medical conditions, and how you’ve responded to medications in the past. If what you’re doing now isn’t working, it’s time for a change. Don’t hesitate to ask your rheumatologist about other options.
It’s hard to say for sure. There’s evidence that exercise is good for people with PsA in many ways. But there’s not much research on flares in particular. Gentle stretching or low-impact activities like walking might help you loosen up a bit when you’re feeling bad. But resting painful joints might be more helpful. A good rule of thumb is to listen to your body. If something makes you hurt worse, don’t do it.
The bottom line
It can be tough to tell the difference between a PsA flare and an infection. Is the infection triggering the flare, or is the infection itself causing the joint pain? If you’re worried about either, call your rheumatologist to discuss your options. They can help figure out what to do next.
Why trust our experts?
Images used with permission from VisualDx (www.visualdx.com).
References
Donvito, T. (2019). What is dactylitis? The ‘sausage finger’ swelling you should know about. CreakyJoints.org.
Donvito, T. (2019). What is enthesitis? The painful arthritis symptom you should know about. CreakyJoints.org.
Earwood, J. S., et al. (2021). Septic arthritis: Diagnosis and treatment. American Family Physician.
Johns Hopkins Medicine. (n.d.). The immune system.
Kessler, J., et al. (2021). Psoriatic arthritis and physical activity: A systematic review. Clinical Rheumatology.
