Theophylline Levels: What You Need to Know About Monitoring and Safety

When you're taking theophylline, a bronchodilator used to treat asthma and COPD by relaxing airway muscles. Also known as a methylxanthine derivative, it's a medication that needs careful handling because the difference between a helpful dose and a dangerous one is small. That’s why theophylline levels aren’t just a lab number—they’re a lifeline. Too low, and your breathing won’t improve. Too high, and you risk seizures, irregular heartbeat, or even death.

This drug doesn’t play nice with other things. smoking, a behavior that speeds up how fast your body breaks down theophylline can make your levels drop, so you might need more. certain antibiotics, like ciprofloxacin or erythromycin, do the opposite—they slow down clearance and can push levels into the danger zone. Even coffee, a common source of caffeine that competes with theophylline in the liver, can interfere. Your doctor won’t just check your levels once—they’ll track them over time because your body changes, your diet changes, and other meds come and go.

People on theophylline often get confused because it’s not like most asthma inhalers. You can’t feel it working right away, and side effects sneak up. Nausea, headaches, jitteriness—these aren’t just "bad days." They’re early warning signs. That’s why regular blood tests aren’t optional. If your levels are off, your doctor might adjust your dose, switch timing, or even change your drug entirely. You’ll find posts here that explain how to spot toxicity before it’s an emergency, why some people need more frequent checks, and how to avoid interactions with common OTC meds and supplements.

There’s no one-size-fits-all number for theophylline levels. Therapeutic range? Usually 10 to 20 mcg/mL. But even within that, your ideal level depends on your age, liver health, and what else you’re taking. This collection doesn’t just list facts—it shows you how real people manage this drug, what went wrong, and how they got it right. Whether you’re on it now, helping someone who is, or just trying to understand why your doctor keeps ordering blood work, you’ll find clear, no-fluff answers below.