context: If other psoriasis treatments don't work the way you want, your doctor may suggest a drug that fights the causes, rather than just eases the symptoms. These drugs are called biologics. They target a specific part of your immune system. The drugs block certain cells or proteins that play a role in psoriasis. They keep them from going into overdrive. While that helps with inflammation and other issues, it also lowers your body's defenses. A weaker immune system could make you more vulnerable to infections or diseases. It could also make a condition your body has under control, such as tuberculosis ( TB), flare up again. While taking the drugs, it's important to watch for signs of an infection such as fever, chills, and feeling tired or achy. You need to call your doctor if you have any of those signs. You get some biologics as shots under the skin. With most of those, your doctor or nurse will show you how to do it, then you'll give them to yourself at home. Others are given intravenously ( IV). That means the medicine drips into a tube and goes through a needle into a vein in your arm. That's done in your doctor's office. Researchers are always testing new biologics, and new ones may be approved down the road. What it treats: Psoriatic arthritis How you take it: You can get it in a prefilled pen or autoinjector and give yourself a shot once a week. Your doctor may start you off with an intravenous dose, then have you give yourself a shot the next day. Or you can get IV doses only. The procedure will take about half an hour. You'll get another dose 2 weeks later and a third dose 2 weeks after that. Then, you'll get infusions every 4 weeks. What it treats: Plaque psoriasis and psoriatic arthritis How you take it: With this, you give yourself a shot every other week. Side effects include serious infections (like tuberculosis), higher chances of certain types of cancer (like lymphoma), and autoimmune disorders, such as a lupus-like syndrome. People who have heart failure or multiple sclerosis shouldn't take it. What it treats: Plaque psoriasis How you take it: This medicine comes in a prefilled syringe, and you get one shot a week for 3 weeks. Then you take one every other week after that. Some people who take it may have a greater risk of thoughts and actions of suicide. So the FDA recommends that doctors weigh the risks and benefits of the medicine before suggesting it for people who have had depression or suicidal thoughts in the past. What it treats: Psoriasis and psoriatic arthritis How you take it: It comes in a prefilled syringe. You'll give yourself two shots on day one, then 2 weeks later, then 2 weeks after that. Then you can choose between one dose every 2 weeks, or two doses every 4 weeks. Let your doctor know if you have signs of an infection like cough, fever, or red and painful skin. Don't take it if you have MS or an inflammatory autoimmune disorder such as Crohn's disease or ulcerative colitis. What it treats: Plaque psoriasis and psoriatic arthritis How you take it: This is another shot you give yourself -- twice a week for 3 months. After that, it's one shot a week. Side effects include skin irritation and rashes. You shouldn't take it if you have multiple sclerosis, a weak immune system, hepatitis B, or heart failure. What it treats: Psoriatic arthritis How you take it: It comes either in a prefilled syringe (needle) or an automatic injector (pen). You'll give yourself a shot every 4 weeks after 3 starter injections. Like other biologics, this makes you more likely to get an infection. You'll need to be tested for tuberculosis and hepatitis B before you start it. What it treats: Plaque psoriasis How you take it: This drug also comes in a prefilled syringe. After your first shot, you'll get another 4 weeks later, then one every 8 weeks. Side effects can include: Headaches Diarrhea or other stomach issues Pain or swelling in your joints Upper respiratory infections What it treats: Plaque psoriasis and psoriatic arthritis How you take it: You get this through an IV, and each session lasts 2 to 3 hours. You'll follow up 2 weeks and 6 weeks after the first dose. Then you'll have treatments every 8 weeks. What it treats: Plaque psoriasis and psoriatic arthritis How you take it: This is a shot you give yourself every 2 weeks for 12 weeks, then once every 4 weeks after that. Some of the most common side effects are: Upper respiratory infections Nausea Fungal infections Your doctor will check you for TB before prescribing this medication and watch you for signs of the disease while you use it. What it treats: Plaque psoriasis How you take it: This comes in a prefilled syringe or a pen. You give yourself two in doses, 4 weeks apart for the initial treatment and then once every 12 weeks after that. The most common side effects are: Upper respiratory infection Headache Fatigue Reactions at the injection site Your doctor will check to make sure you don't have TB before you start treatment and will watch you closely for signs of the disease while you're on it. What it treats: Plaque psoriasis and psoriatic arthritis How you take it: This comes in a prefilled syringe or a pen. You give yourself one dose a week for 5 weeks, then once a month after that. The most common side effects are: Symptoms of a cold Upper respiratory infection Diarrhea Your doctor will check to make sure you don't have TB before you start treatment and will watch you closely for signs of the disease while you're on it. What it treats: Plaque psoriasis and psoriatic arthritis How you take it: After the first shot, you get another 4 weeks later. Then you get one every 12 weeks. It makes your psoriasis patches thinner and eases scaling and redness. But it also can make you more likely to have certain kinds of cancer or a rare condition called reversible posterior leukoencephalopathy, a serious illness that affects your brain. It depends on 5 things: 1. How much of your skin is affected by psoriasis Doctors often use biologic drugs on people with moderate to severe psoriasis. Moderate psoriasis means that 3% to 10% of your body is covered with red, scaly patches. Severe psoriasis means that more than 10% of your body is covered. You may also want to take a biologic drug if you have mild psoriasis but it really bothers you. 2. How much psoriasis affects your life If your psoriasis doesn't really bother you, the doctor may tell you that a biologic drug isn't worth the risks. Biologics suppress your immune system. That means they can make you more likely to get an infection. They may not be worth the cost, either. Biologic drugs are expensive. Depending on the drug and the dose, they can cost $10,000 to $30,000 or more a year. 3. Your health The doctor will take a careful look at your health history. Biologic drugs may not be best for people with certain health conditions, including: A history of infections such as tuberculosis A history of cancer A weak immune system because of a disease like HIV or cancer Biologics may cause a recurrence of some chronic diseases that are in remission. Also, because biologics suppress the immune system, they could make serious infections more likely. 4. Insurance coverage Insurance companies often want doctors to try less expensive treatments first. If those treatments don't work or you have severe psoriasis, then your insurance likely will cover the cost of a biologic drug, 5. Your preferences A biologic drug won't help if you're too afraid to take it. You get biologics by a shot or by IV infusion. If you're afraid of needles, it might be easier to take an oral drug or topical treatment instead. Whether you start with a biologic drug or turn to one after trying other therapies, you should see dramatic results. But you need to follow your doctor's instructions for any treatment carefully. And you'll need to go in for regular follow-up visits to make sure your treatment is still working. At your visits, talk about any problems or side effects you are having.