How do PsA and OA differ?

Arthritis isn’t one disease. The term describes more than 100 different kinds of joint damage and pain. Psoriatic arthritis (PsA) and osteoarthritis (OA) are two of the most common forms of arthritis.

PsA is an autoimmune disease. It causes joint swelling, stiffness, and pain. PsA also causes symptoms of psoriasis, such as a scaly red skin rash and nail pitting. Some cases of PsA are mild and only rarely cause problems. Others can be more severe and even debilitating.

OA is an age-related type of arthritis caused by wear and tear on the joints. It’s the most common type of arthritis. It affects more than 30 million Americans.

Sometimes the cause of joint pain and other arthritis symptoms isn’t clear. If PsA affects your joints before your skin, it may be hard to tell it apart from OA. Your symptoms, genealogy, and test results can help your doctor figure out which type of arthritis you have and the best way to treat it.

Keep reading to learn more about each type, including common identifiers, who’s at risk, and potential treatment options.

Psoriatic arthritis and osteoarthritis share some symptoms, but they also have key differences.

SymptomPsoriatic arthritis (PsA) onlyOsteoarthritis (OA) onlyPsA and OA
Swollen fingers and toes
Tendon or ligament pain
Red rash
Silvery-white patches
Nail pitting or other changes
Eye redness
Eye pain
Grinding or clicking during movement
Hard lumps of bone near joint
Distorted joint shape
Joint pain
General swelling
Reduced flexibility

Tips for identifying PsA

Symptoms of PsA are often confused with symptoms of OA or rheumatoid arthritis (RA). The key to distinguishing between PsA and the other forms of arthritis is to single out unique characteristics.

Key symptoms that distinguish PsA from OA and other forms of arthritis are:

Swelling in your fingers or toes

In PsA, the fingers and toes can swell up like sausages, a symptom that’s called dactylitis.

Skin rashes

The buildup of skin cells in psoriasis causes the skin to thicken and turn red. The redness may be topped with silvery-white patches.

You’ll most often notice these rashes, which are called plaques, on your scalp, face, hands, feet, genitals, and in skin folds like your belly button.

Nail changes

About 80 percent of people with PsA have pitted, thickened, or discolored nails.

Both OA and PsA affect similar joints, including the:

  • lower back
  • fingers
  • toes
  • knees

But while OA pain is consistent, PsA comes and goes in flares. In other words, the symptoms of the condition grow worse for a period of time, and then go into remission, or periods of inactivity.

Tips for identifying OA

OA isn’t a disease that cycles, like PsA. Instead, it can gradually get worse.

OA pain may be mild at first. You might notice a slight twinge in your knee when you bend it, or your joints might ache after a workout.

The pain, swelling, and stiffness will get worse as the joint damage increases. Along with the pain, your joints will feel stiff — especially when you first wake up in the morning.

OA will most likely affect the joints of your body that move the most.

This includes the joints in your:

  • hands
  • feet
  • knees
  • hips
  • spine

PsA is an autoimmune disease. Autoimmune diseases cause your body to mistakenly attack its own cells.

PsA typically only develops in people who have psoriasis. Psoriasis is a common skin condition that causes rapid skin cell buildup. The excess skin cells form red patches, which are often covered in whitish-silvery scales.

About 7.5 million Americans have psoriasis. Between 20 to 30 percent of people with psoriasis also have PsA.

In most people with PsA, psoriasis develops first. The arthritis usually starts later. About 15 percent of the time, arthritis starts before a skin rash appears.

Other risk factors for PsA include:

  • Family history. About 40 percent of people with a parent, sibling, or other close relative who has psoriasis or PsA will get this condition.
  • Age. This form of arthritis can develop at any age, but it’s most commonly diagnosed in people ages 30 to 50.
  • Infections. People who are exposed to certain viruses, such as HIV, are more likely to get PsA.

Treatments for PsA aim to do two things: Slow or stop the joint damage and relieve pain.

A typical treatment plan will involve one or more of the following:

  • medication
  • steroid injections
  • joint replacement surgery
  • alternative remedies

There are also treatments for psoriasis skin rashes and nail changes.

Medications and injections

Nonsteroidal anti-inflammatory drugs (NSAIDs) relieve pain and bring down swelling in your joints. Some of these medications are available over the counter (OTC). Others require a prescription from your doctor.

OTC options include ibuprofen (Advil) and naproxen (Aleve).

Common prescription options include:

Disease-modifying antirheumatic drugs (DMARDs) reduce the overactive immune system response. They can slow or stop joint damage.

Commonly prescribed DMARDs include:

New guidelines recommend biologic drugs as first-line treatments for PsA. These drugs work on specific parts of your immune system to stop joint damage. You get them as an injection or infusion.

Commonly prescribed biologic drugs include:

New drugs for PsA target certain molecules inside the immune cell. One such drug is apremilast (Otezla).

In addition to these medications, steroid injections into the affected joint can bring down swelling and relieve pain. If the joint is badly damaged, surgery is an option to fix or replace it.

Alternative treatments

A few alternative therapies have also been studied for PsA. Ask your doctor if it’s worth trying one or more of these techniques:

  • acupuncture
  • herbal remedies such as capsaicin or turmeric
  • massage
  • tai chi
  • yoga

Treatments targeting psoriasis symptoms

Some of the medications that manage arthritis symptoms, like biologics and methotrexate, also treat the skin symptoms that often result from the associated psoriasis.

Other treatments for the skin include:

  • anthralin (Dritho-Scalp)
  • coal tar
  • retinoid creams, such as tazarotene (Tazorac)
  • salicylic acid
  • steroid creams and ointments
  • vitamin D-based creams, such as calcipotriene (Dovonex)

You can also try light therapy (phototherapy). This treatment uses ultraviolet light to clear plaques on your skin.

Physical or occupational therapies are recommended for PsA patients to maintain joint health and improve their quality of life.

OA causes the cartilage inside the joints to break down and wear away. Cartilage is the flexible connective tissue that surrounds the ends of your bones.

In healthy joints, cartilage helps grease the movement of the joint and absorbs the shock of impact when you move. When you have OA, the layers of your cartilage begin to break down.

Without cartilage, your bones rub painfully against each other. This can cause permanent damage to both your joints and your bones.

These risk factors can increase your chances of developing OA:

  • Genes. Certain inherited genetic changes may increase your odds of developing OA. If a family member has the disease, it’s possible you’ll get it as well.
  • Age. Your likelihood of getting this type of arthritis increases as you age.
  • Gender. Women are more likely than men to develop all kinds of arthritis, including OA.
  • Weight. People who are overweight or obese have a higher risk because of the extra strain on their joints.
  • Joint damage. If your joints were injured or didn’t form properly, they can get damaged more easily.
  • Smoking. Tobacco smoking doesn’t cause OA, but it can accelerate cartilage damage.

OA treatment aims to reduce the symptoms of the condition.

A typical treatment plan will include one or more of the following:

  • medication
  • injections
  • exercise or physical therapy
  • joint support, such as braces
  • alternative remedies

If your joint is badly damaged, you may need surgery. OA surgery replaces the damaged joint with an artificial joint made from plastic or metal.


Medications for OA relieve joint pain and swelling.

OTC options include acetaminophen (Tylenol) and NSAIDs, such as ibuprofen (Advil) and naproxen (Aleve). Duloxetine (Cymbalta) is available by prescription only.

Some medications are injected right into the joint to reduce inflammation and increase movement. These include corticosteroids and hyaluronic acid.

Alternative treatments

Alternative treatments can help you manage symptoms and cope with changes in your abilities as OA progresses.

Popular options include:

  • acupuncture
  • assistive devices, such as splints, shoe orthotics, canes, walkers, and scooters
  • massage
  • meditation and other relaxation techniques
  • occupational therapy
  • physical therapy
  • water therapy


Exercise strengthens the muscles that support your joints. Regular physical activity can also help control your body weight, which can alleviate stress on the joints in your knees and hips.

The ideal exercise program for OA combines low-impact aerobics with strength training. Add in yoga, Pilates, or tai chi to improve your flexibility.

If you have joint pain, swelling, and stiffness that doesn’t go away after a few weeks, see your doctor. You should also see your doctor if you notice a rash in areas like your scalp, face, or under your arms.

If you do have PsA or OA, starting treatments and making lifestyle changes can help you limit further damage and preserve the joint strength you still have.