Drug & supplement interaction

Melatonin + Lactic Acid, Citric Acid, Potassium Bitartrate

Lactic Acid, Citric Acid, Potassium Bitartrate brand name: Phexxi.

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

Melatonin has a moderate interaction with Lactic Acid, Citric Acid, Potassium Bitartrate. Theoretically, taking contraceptive drugs with melatonin might increase the effects and adverse effects of melatonin.

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

Melatonin and Lactic Acid, Citric Acid, Potassium Bitartrate

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CONTRACEPTIVE DRUGS

Why this applies to Lactic Acid, Citric Acid, Potassium Bitartrate

Lactic Acid, Citric Acid, Potassium Bitartrate falls under CONTRACEPTIVE DRUGS — the group Melatonin interacts with.

Theoretically, taking contraceptive drugs with melatonin might increase the effects and adverse effects of melatonin.
Contraceptive drugs can increase the levels of endogenous melatonin. Theoretically, these drugs may increase the effects and adverse effects of oral melatonin.
Severity Moderate Likelihood Probable Evidence B

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 some good news if you use Phexxi (lactic acid, citric acid, and potassium bitartrate) and also take melatonin: this particular interaction really doesn't apply to you in a meaningful way. The concern on file is about hormonal birth control, like the pill, which can raise your body's own melatonin levels and make a melatonin supplement feel a bit stronger (think extra drowsiness or grogginess).

Phexxi is different. It's a non-hormonal vaginal gel that works locally by lowering the pH in the vagina to slow sperm. It isn't absorbed in a way that changes your melatonin levels, so it shouldn't boost melatonin's effects. The evidence behind this warning is also weak and mostly theoretical. Still, if you ever feel unusually sleepy or off, check in with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Wright KP Jr, Myers BL, Plenzler SC, et al. Acute effects of bright light and caffeine on nighttime melatonin and temperature levels in women taking and not taking oral contraceptives. Brain Res 2000;873:310-7.

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

Melatonin Also Interacts With Other Medications

Melatonin has 1,116 moderate, 346 minor known drug interactions in our database — the Lactic Acid, Citric Acid, Potassium Bitartrate one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,116 Minor 346 No known interaction 1,368 (incl. Lactic Acid, Citric Acid, Potassium Bitartrate)
Taking anything else?

Check Another of Your Medications Against Melatonin

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

From our Q&A

Questions About Melatonin or Lactic Acid, Citric Acid, Potassium Bitartrate

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Melatonin or Lactic Acid, Citric Acid, Potassium Bitartrate, 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 Lactic Acid, Citric Acid, Potassium Bitartrate

This page covers Melatonin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Lactic Acid, Citric Acid, Potassium Bitartrate page lists 33 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: St. John's Wort (major), Activated Charcoal (moderate), Alfalfa (moderate), Anise (moderate) and Black Tea (moderate).

By severity: 1 major · 21 moderate · 11 minor.

From our pharmacist’s overview on the Lactic Acid, Citric Acid, Potassium Bitartrate page

“St. John's wort is the entry I would not brush past.”

Reviewed by 2 · Jul 18, 2026

Open the Lactic Acid, Citric Acid, Potassium Bitartrate interaction page

One more smart check

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

We hold 2,885 real supplement products containing Melatonin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Melatonin. Your product may carry other ingredients that interact with Lactic Acid, Citric Acid, Potassium Bitartrate too, on top of Melatonin — 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 Melatonin and Lactic Acid, Citric Acid, Potassium Bitartrate 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 Melatonin
Top 5%

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

29 days ago today
Medication Lactic Acid, Citric Acid, Potassium Bitartrate
Top half

#903 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 Melatonin

What is Melatonin?

Melatonin
  • Trouble falling asleep (insomnia)
  • Jet lag
  • Delayed sleep phase syndrome
  • Non-24-hour sleep-wake disorder
  • Shift-work sleep problems
  • Sleep problems in some children with conditions like autism or ADHD

Melatonin is a hormone your body makes naturally to help control your sleep-wake cycle, and the supplement form is widely used to help with sleep timing problems and jet lag. The evidence is strongest for certain circadian (body-clock) disorders and is more mixed for everyday insomnia. It is generally well tolerated for short-term use, but talk with your pharmacist or doctor before starting, especially for children or during pregnancy.

Read the full Melatonin monograph & all interactions
Medication

About Lactic Acid, Citric Acid, and Potassium Bitartrate Vaginal Contraceptive

What Is Lactic Acid, Citric Acid, and Potassium Bitartrate Vaginal Contraceptive Used For?

Brand name: Phexxi

PHEXXI is used to prevent pregnancy in people who can become pregnant. It's an on-demand contraceptive, meaning you use it only when you need it — right before vaginal sex.

Important to know: PHEXXI does not work if you use it after intercourse. It must be applied beforehand to be effective.

See full Lactic Acid, Citric Acid, and Potassium Bitartrate Vaginal Contraceptive drug information
Keep checking

Other Drugs & Melatonin

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

0Major
1,116Moderate
346Minor
1,367No known interaction
1,116 Moderate 346 Minor 1,367 No interaction
Moderate

1,116 interactions

Showing 60 of 1,116 moderate interactions — see all 1,116 on the Melatonin page.

Minor

346 interactions

Showing 60 of 346 minor interactions — see all 346 on the Melatonin page.

No interaction 1,367 drugs checked — show the list

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

Showing the 60 most looked-up of 1,367 medications checked with no known interaction — see the full Melatonin list.

See the full Melatonin interactions page
See every supplement checked against Lactic Acid, Citric Acid, Potassium Bitartrate, 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
Melatonin monograph › Uses, safety, and every drug interaction in one place Lactic Acid, Citric Acid, Potassium Bitartrate supplement interactions › Every supplement checked against Lactic Acid, Citric Acid, Potassium Bitartrate, ranked by severity Lactic Acid, Citric Acid, and Potassium Bitartrate Vaginal Contraceptive drug information › The full plain-English guide to this medication 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 Melatonin and Lactic Acid, Citric Acid, Potassium Bitartrate Together: Common Questions

Can you take Melatonin with Lactic Acid, Citric Acid, Potassium Bitartrate?
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.
How serious is the Melatonin and Lactic Acid, Citric Acid, Potassium Bitartrate 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 Lactic Acid, Citric Acid, Potassium Bitartrate and Melatonin?

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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.