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Prednisone

Brand names: Rayos

Prednisone is a steroid medicine that calms inflammation and the immune system. It's used for flare-ups of asthma, arthritis, allergies, and many other conditions.

Brand namesRayos
Type of medicineCorticosteroid (steroid)
Prescription?Prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It acts like cortisol, a hormone your body makes. Short courses are common; long-term use needs closer monitoring.

What it's used for

  • Asthma and COPD flare-ups
  • Severe allergic reactions and skin rashes
  • Rheumatoid arthritis, lupus, and other autoimmune diseases
  • Inflammatory bowel disease flares
  • Some cancers and organ transplants

How to take it

  • Take it with food in the morning to reduce stomach upset and trouble sleeping.
  • If you've taken it longer than a couple of weeks, don't stop suddenly. Your provider will lower the dose slowly.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Increased appetite and weight gain
  • Trouble sleeping
  • Mood swings or irritability
  • Higher blood sugar
  • Fluid retention
Call 911Black or bloody stools or vomiting blood
Call your provider todayFever, chills, or other signs of infection
Call your provider todayVery high blood sugar: extreme thirst, peeing a lot, or confusion
Call your provider todaySevere mood changes, confusion, or seeing or hearing things
Call your provider todayEye pain or vision changes

Warnings

  • It lowers your ability to fight infection. Avoid people with chickenpox or measles.
  • Long-term use can cause bone thinning, cataracts, high blood pressure, and diabetes.
  • Ask before getting live vaccines.

Other medicines, foods, and alcohol

  • NSAIDs raise the risk of stomach ulcers.
  • It can raise blood sugar, so diabetes medicines may need adjusting.
  • Some seizure medicines and rifampin lower its effect.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Sometimes needed in pregnancy. Talk with your provider about benefits and risks.

Missed doses, overdose, and storage

If you miss a dose

Take it as soon as you remember, unless it's almost time for your next dose. Then skip the missed dose. Don't take two doses at once.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.