Drug & supplement interaction

Caffeine + Ephedrine Sulfate, Hydroxyzine, Theophylline

Ephedrine Sulfate, Hydroxyzine, Theophylline brand name: Hydroxy Compound.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Ephedrine Sulfate, Hydroxyzine, Theophylline falls into 2 drug categories that Caffeine can interact with; the most serious is rated moderate. Theoretically, concomitant use might increase stimulant adverse effects.

Read the full interaction report
SeverityModerate
LikelihoodProbable
Interactions2
EvidenceC
What do Severity, Likelihood & Evidence mean?
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Interaction report

Caffeine and Ephedrine Sulfate, Hydroxyzine, Theophylline

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Caffeine interacts with whole categories of medication. Ephedrine Sulfate, Hydroxyzine, Theophylline falls into 2 of those categories, so it can interact with Caffeine in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

STIMULANT DRUGS

1 of 2

Why this applies to Ephedrine Sulfate, Hydroxyzine, Theophylline

Ephedrine Sulfate, Hydroxyzine, Theophylline falls under STIMULANT DRUGS — the group Caffeine interacts with.

Theoretically, concomitant use might increase stimulant adverse effects.
Due to the central nervous system (CNS) stimulant effects of caffeine, concomitant use with stimulant drugs can increase the risk of adverse effects.
Severity Moderate Likelihood Probable Evidence C

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the simple version: caffeine is a stimulant, and so are ephedrine and theophylline. When you stack stimulants, their effects can add up. That's why mixing caffeine with this combo product may leave you feeling jittery, shaky, or anxious, with a faster or pounding heartbeat and trouble sleeping. Theophylline in particular is closely related to caffeine, so the overlap can be noticeable. Hydroxyzine is more of a calming antihistamine, so it isn't the part driving this concern.

This is more of a common-sense, expert-opinion caution than a hard rule, but it makes sense. Everyday coffee or tea may be fine, while energy drinks or caffeine pills are more likely to push things too far. Check with your pharmacist or doctor about your usual intake.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington, DC: National Academy Press, 2001. Available at: http://books.nap.edu/books/0309082587/html/index.html. DOI
Moderate

THEOPHYLLINE

2 of 2

Ephedrine Sulfate, Hydroxyzine, Theophylline also falls under THEOPHYLLINE.

Theoretically, caffeine might increase the levels and adverse effects of theophylline.
Large amounts of caffeine might inhibit theophylline metabolism.
Severity Moderate Likelihood Probable Evidence C

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing with this combo: your body uses the same cleanup pathway (the liver enzyme CYP1A2) to break down both caffeine and the theophylline in your medicine. When you take in a lot of caffeine, it can hog that pathway and slow down how fast theophylline leaves your system. That lets theophylline levels creep up.

Why does that matter? Theophylline is a narrow-therapeutic-index drug, meaning the gap between a helpful dose and a too-much dose is small. Even modest changes can tip you over. Watch for a racing or pounding heart, jitteriness, nausea, trouble sleeping, or feeling shaky, and remember the ephedrine in this product is also a stimulant that adds to that. This is based mostly on expert opinion, and a morning cup of coffee is different from energy drinks or caffeine pills. Please check with your pharmacist or doctor before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Carrillo JA, Benitez J. Clinically significant pharmacokinetic interactions between dietary caffeine and medications. Clin Pharmacokinet 2000;39:127-53. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Caffeine Also Interacts With Other Medications

Caffeine has 8 major, 482 moderate, 164 minor known drug interactions in our database — the Ephedrine Sulfate, Hydroxyzine, Theophylline one above is among them. If you take anything else, check it against the full list below.

Major 8 Moderate 482 Minor 164 No known interaction 2,176 (incl. Ephedrine Sulfate, Hydroxyzine, Theophylline)
Taking anything else?

Check Another of Your Medications Against Caffeine

Covers the 2,830 medications we’ve checked against Caffeine. Pick one to open its full report.

From our Q&A

Questions About Caffeine or Ephedrine Sulfate, Hydroxyzine, Theophylline

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Caffeine or Ephedrine Sulfate, Hydroxyzine, Theophylline, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Ephedrine Sulfate, Hydroxyzine, Theophylline

This page covers Caffeine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ephedrine Sulfate, Hydroxyzine, Theophylline page lists 199 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Henbane (major), Peyote (major) and Rauvolfia Vomitoria (major).

By severity: 7 major · 153 moderate · 39 minor.

From our pharmacist’s overview on the Ephedrine Sulfate, Hydroxyzine, Theophylline page

“Someone taking Hydroxy Compound (ephedrine sulfate, hydroxyzine, and theophylline) for breathing problems is juggling three drugs at once, and the supplement list shows it: 199 interacting ingredients, seven of them rated major, and this page deserves genuine seriousness. The sharpest risks come from stimulant botanicals, ephedra above…”

Reviewed by 2 · Jul 18, 2026

Open the Ephedrine Sulfate, Hydroxyzine, Theophylline interaction page

One more smart check

Taking Caffeine as Part of a Dietary Supplement Product? Check It for Interactions

We hold 6,775 real supplement products containing Caffeine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Caffeine. Your product may carry other ingredients that interact with Ephedrine Sulfate, Hydroxyzine, Theophylline too, on top of Caffeine — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Caffeine and Ephedrine Sulfate, Hydroxyzine, Theophylline Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Caffeine
Top 5%

#25 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ephedrine Sulfate, Hydroxyzine, Theophylline
Top half

#1,102 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Caffeine

What is Caffeine?

  • Mental alertness and reducing fatigue
  • Improving athletic performance
  • Headache and migraine relief
  • Boosting focus and concentration
  • Weight loss aid

Caffeine is a natural stimulant found in coffee, tea, and many other plants and products. In moderate amounts it can boost alertness and reduce tiredness for most healthy adults, but too much can cause jitteriness, a racing heart, and sleep problems. Pregnant women and people with heart conditions or anxiety should be especially careful and check with a doctor or pharmacist.

Read the full Caffeine monograph & all interactions
Keep checking

Other Drugs & Caffeine

Browse every other medication we’ve checked against Caffeine — both the ones with a known interaction and the ones without. Select any drug for the full detail.

8Major
482Moderate
164Minor
2,175No known interaction
8 Major 482 Moderate 164 Minor 2,175 No interaction
Major

8 interactions

Moderate

482 interactions

Showing 60 of 482 moderate interactions — see all 482 on the Caffeine page.

Minor

164 interactions

Showing 60 of 164 minor interactions — see all 164 on the Caffeine page.

No interaction 2,175 drugs checked — show the list

We also checked Caffeine against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,175 medications checked with no known interaction — see the full Caffeine list.

See the full Caffeine interactions page
See every supplement checked against Ephedrine Sulfate, Hydroxyzine, Theophylline, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Caffeine monograph › Uses, safety, and every drug interaction in one place Ephedrine Sulfate, Hydroxyzine, Theophylline supplement interactions › Every supplement checked against Ephedrine Sulfate, Hydroxyzine, Theophylline, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Caffeine and Ephedrine Sulfate, Hydroxyzine, Theophylline Together: Common Questions

Can you take Caffeine with Ephedrine Sulfate, Hydroxyzine, Theophylline?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Caffeine and Ephedrine Sulfate, Hydroxyzine, Theophylline?
Ephedrine Sulfate, Hydroxyzine, Theophylline belongs to more than one drug category, and Caffeine interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Caffeine and Ephedrine Sulfate, Hydroxyzine, Theophylline interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Ephedrine Sulfate, Hydroxyzine, Theophylline and Caffeine?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.