Aminophylline: what it treats, how to take it, side effects
Last updated September 7, 2026.
**Aminophylline is a xanthine bronchodilator, a salt that combines theophylline with ethylenediamine and relaxes the muscle wrapped around your airways.** In the body it releases theophylline, which blocks adenosine receptors and phosphodiesterase enzymes in airway smooth muscle, so narrowed breathing tubes open up and the diaphragm works with more force. The effect builds over hours rather than seconds, which is why it is a maintenance medicine and not a rescue inhaler. The most important safety point is the narrow blood level window: the useful range of about 10 to 20 mcg/mL of theophylline sits close to the range that causes vomiting, fast heart rhythms, and seizures, so blood tests and interaction checks matter more here than with inhaled drugs.
What does it treat?
Aminophylline treats reversible airway narrowing: asthma, and the chronic bronchitis and emphysema sides of COPD. Doctors reach for it when inhalers alone leave someone with a pattern of nighttime or early morning wheeze, chest tightness on waking, coughing that breaks up sleep, or breathlessness on stairs that persists on a steady inhaler regimen. The injectable form is given in hospitals for severe asthma attacks that are not settling with nebulized treatment, and in neonatal units for apnea of prematurity. In the United States today it is almost always a single-ingredient product; older combination tablets and elixirs that mixed theophylline with guaifenesin, ephedrine, or phenobarbital are no longer marketed here, so if you see one in an old medicine cabinet, bring it to your doctor rather than taking it.
How do you take it?
Aminophylline comes as immediate-release tablets (usually 100 mg and 200 mg), extended-release tablets, an oral liquid, and a solution for intravenous infusion given in hospital. A common adult start for oral therapy is about 500 mg a day, or roughly 20 mg per kilogram of body weight a day if that is less, split into doses every 6 to 8 hours; the dose is then raised in steps of about 25 percent every 3 days if you are tolerating it. The usual adult ceiling is about 1,100 mg of aminophylline a day (equal to 900 mg of theophylline) or 13 mg per kilogram a day, whichever is lower, and going above that is done only when a blood level shows it is needed. Take each dose at the same times every day and keep your relationship to food consistent, since switching an extended-release dose between empty stomach and a heavy fatty meal can change how fast the drug is absorbed; swallow extended-release tablets whole unless your pharmacist confirms yours is scored for splitting. If you miss a dose, take it when you remember, but skip it if your next dose is close, and never take two doses together. Stop and call your doctor if you get repeated vomiting, a persistent headache, shakiness, trouble sleeping that is new, or a heartbeat that feels fast or irregular, because those are the signals that your level has climbed too high.
Side effects to know
- Common: Many people settle in with no trouble, and the usual early effects are mild nausea, stomach upset, restlessness, a jittery feeling, headache, or trouble falling asleep, which often ease as your body adjusts to a steady dose.
- Serious: Stop the drug and get medical help right away for repeated vomiting, a fast or pounding or irregular heartbeat, confusion, tremor you cannot control, or a seizure, since these point to theophylline toxicity. Also stop and seek care for a spreading rash, blistering or peeling skin, or facial and throat swelling, because the ethylenediamine in aminophylline can trigger allergic skin and airway reactions.
Who should not take it?
Do not take aminophylline if you have had an allergic reaction to theophylline or to ethylenediamine, and talk to your doctor first if you have a seizure disorder, an active stomach ulcer, an irregular or fast heart rhythm, heart failure, liver disease, an overactive thyroid, or if you are over 60, since your body clears the drug more slowly. Many medicines change your theophylline level: cimetidine, ciprofloxacin, erythromycin and clarithromycin, fluvoxamine, zileuton, allopurinol in high doses, and propranolol push it up, while rifampin, phenytoin, carbamazepine, phenobarbital, and St. John's wort pull it down. Smoking speeds clearance, so quitting smoking or vaping nicotine can raise your level within about a week even though your dose has not changed, and the same is true of a fever or a flu-like illness. In pregnancy the current FDA labeling reports no controlled human studies and advises use only when the benefit justifies the risk, with level checks because clearance shifts in the third trimester; theophylline passes into breast milk and can make a nursing infant irritable and wakeful, so tell your doctor if you are breastfeeding rather than stopping on your own. Alcohol slows the breakdown of theophylline, so keep drinking light and occasional, skip binge drinking entirely, and hold your caffeine intake roughly steady day to day.
When is it an emergency?
Call 911 if you have a seizure, collapse, cannot catch your breath, have chest pain, or your heartbeat is racing and irregular with lightheadedness. Call Poison Control at 1-800-222-1222 right away if you or a child takes extra aminophylline tablets or a double dose, even if nothing feels wrong yet, because overdose can start quietly with repeated vomiting, tremor, agitation, and a fast pulse and then move to dangerous heart rhythms or seizures. Get emergency help for swelling of the lips, tongue, or throat, hives with breathing trouble, or skin that is blistering or peeling. If your rescue inhaler is not touching an asthma attack, treat that as an emergency and go to the emergency department rather than waiting for your aminophylline dose to work.
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Common questions
What is the maximum dose of aminophylline for an adult?
For most adults the usual ceiling is about 1,100 mg of aminophylline a day, which delivers roughly 900 mg of theophylline, or 13 mg per kilogram of body weight a day, whichever works out lower. That total is split into doses every 6 to 8 hours for immediate-release tablets, or every 8 to 12 hours for extended-release forms. Doctors only go above that ceiling when a blood level shows the drug is being cleared unusually fast, and they recheck the level afterward. If you are over 60, have heart failure, or have liver disease, your safe maximum is lower because your body clears theophylline more slowly.
Can I drink alcohol while taking aminophylline?
Alcohol slows the enzyme that breaks down theophylline, so drinking can raise your blood level even though your dose has not changed. A light, occasional drink is generally manageable for most people, but heavy or binge drinking is not, because that is when levels climb into the range that causes vomiting and heart rhythm problems. Alcohol also worsens acid reflux and disturbs sleep, and aminophylline already tends to do both. Tell your doctor honestly how much you drink so your dose and level checks can be set around it.
Is aminophylline safe in pregnancy or while breastfeeding?
The FDA labeling notes there are no adequate controlled studies in pregnant women and advises using aminophylline only when the benefit to you justifies the possible risk. Poorly controlled asthma carries real risk in pregnancy too, so the decision is usually about keeping your breathing stable rather than stopping the drug outright. If you continue it, expect more frequent theophylline level checks, because clearance changes in the third trimester and a dose that was right earlier can drift. Theophylline passes into breast milk and can make a nursing baby irritable and wakeful, so tell your doctor if you are breastfeeding; timing doses right after a feeding sometimes helps.
Should I take aminophylline with food?
The rule is consistency more than timing. Taking an extended-release dose with a large high-fat meal one day and on an empty stomach the next can change how fast the drug is absorbed and swing your level. Pick empty stomach with water, or with the same kind of meal, and stick to it every day. If plain tablets upset your stomach, taking them with food is fine as long as you do it the same way each dose. Keep your daily caffeine steady as well, since coffee, tea, and energy drinks add to the same jittery effects.
What are the first signs of an aminophylline overdose?
Repeated vomiting is the classic early warning, often with a headache that will not clear, restlessness, trouble sleeping, and hand tremor. As the level climbs further, the heart can beat fast or irregularly and you may feel lightheaded or confused. In some people, especially with a chronic buildup over days, a seizure can be the first dramatic sign, which is why the earlier symptoms are worth acting on. Call Poison Control at 1-800-222-1222 for any suspected overdose and call 911 for a seizure, collapse, or breathing trouble.
Which medicines interact with aminophylline?
Ciprofloxacin, erythromycin, clarithromycin, cimetidine, fluvoxamine, zileuton, propranolol, and high-dose allopurinol all slow the clearance of theophylline and can raise your level into the toxic range. Rifampin, phenytoin, carbamazepine, phenobarbital, and St. John's wort do the opposite and can drop your level until the drug stops helping your breathing. Nicotine matters too: smoking speeds clearance, so quitting can raise your level within about a week without any dose change. Show every prescriber and pharmacist your full list, including over-the-counter and herbal products, before starting anything new.