Biologic Medications and Side Effects

Medically Reviewed by David Zelman, MD on June 30, 2023
5 min read

Biologic medications are drugs that target specific parts of your immune system to treat disease.

If you have a condition like psoriatic arthritis, biologics can make a big difference. They can ease inflammation in your body, stop joint damage, and improve your quality of life.

But these powerful drugs can also have serious side effects.

Biologic drugs are human-made proteins that are designed to zero in on parts of the immune system that trigger inflammation. They come from a living source (a human or animal) or its products.

Biologics can treat a variety of conditions, such as cancer, psoriasis, rheumatoid arthritis (RA), and inflammatory bowel diseases like Crohn’s disease.

These medicines are given as a shot or through an infusion into a vein.

The side effects of biologics usually depend on the type of medicine you use.

Common side effects of biologic drugs include:

Injection or infusion reactions. You may have a skin reaction where the shot went in, especially when you’re just starting treatment. This might include:

These things should go away on their own. Tell your doctor if they get worse or last longer than 5 days.

Some people who get infusions of biologic medicines have a reaction that can be mild or serious.

Symptoms of a mild reaction can include:

Serious reactions are rare but may include:

Nausea. Biologic drugs can upset your stomach.

Headaches. Headaches are more common in people who use biologic drugs.

Infection. Biologic meds raise your risk of infection because they weaken your immune system. You could get a cold, a sinus infection, an upper respiratory tract infection, bronchitis, or a urinary tract infection (UTI). One study found that people who take these drugs may also be more likely to test positive for COVID-19.

Reactivation of infections. A biologic medicine can cause the return of conditions like hepatitis B or tuberculosis (TB) if you’ve had them before. Your doctor will test you for these infections before you start treatment.

Fatigue. For most people, biologics help treat the fatigue that often comes with an autoimmune condition. But in some, the tiredness may get worse or even last after you stop taking the drug.

Side effects of biologics like these are rarer:

Central nervous system issues. These include sudden vision problems, numbness, or tingling.

Heart problems. Things like shortness of breath or sudden heart failure are possible.

Lupus-like syndrome. This condition can start as a rash that affects your face and arms and gets worse when you’re in the sun.

Cancer. Older studies found that people who took biologic medicines might be more likely to get lymphoma. More recent research shows no link. But some studies have suggested that biologic medicines may slightly raise your risk of certain types of skin cancer.

Liver problems. Biologic medicines may cause a change in how your liver works. Symptoms of liver issues include yellowing of the skin or eyes.

New joint pain. Though biologics are used to treat arthritis, they can sometimes cause new joint pain.

The chances of side effects depend on the type of biologic drug you use, how long you use it, your medical history, and how your body responds to the drug.

One study looked at 1,000 people who took a biologic medication and 1,000 who got a placebo. In the biologic group, 770 reported a side effect -- slightly more than the 724 who reported side effects in the placebo group.

The researchers also found that 127 of 1,000 people who received a biologic reported a serious side effect, compared with 118 of 1,000 who took a placebo.

There are ways to manage, or even prevent, many of the side effects of biologic drugs.

Good hygiene can help you avoid infections when you have a weakened immune system. Wash your hands often, try to avoid crowded places when you can, and stay away from sick people to lower your risk.

If you notice a mild injection site reaction, try a cold compress, an antihistamine medicine, a steroid cream, or acetaminophen to ease the discomfort.

To prevent more serious reactions, your doctor might suggest that you take an antihistamine, antiemetic, or anti-inflammatory medicine before your treatment.

If you have nausea, medicines can help. Or you can suck on ice chips, sip cool water, inhale the scent of peppermint, or drink ginger tea.

To ease a headache, put a cold compress on your forehead for 10 to 15 minutes. You can also take a warm shower or sit quietly in a dim room for a few minutes.

Talk to your doctor if the side effects are affecting your daily life or if you have severe symptoms.

It’s a good idea to read the information packet that comes with your biologic medicine. This has a full list of possible side effects and reactions to watch for.

You may see something called a black box warning, which means the medication has serious safety risks. This sounds scary, but it’s important to remember that all medicines carry some risks.

Your doctor will consider all the risks and benefits when deciding on a prescription. If they recommend one that has a black box warning, it’s because they think it will be more helpful than harmful.

Talk with them if you want to know more or if you’re worried about side effects.