What drug interactions should I know about on a GLP-1?

GLP-1 medications slow stomach emptying, which can affect how your body absorbs other medications. Most common medications don't need dose changes, but some important interactions exist - especially with insulin, sulfonylureas, oral contraceptives (with tirzepatide), and time-sensitive medications like warfarin.

Insulin + sulfonylurea: Taking insulin is an absolute contraindication for GLP-1 therapy and cannot be overridden. If you currently take a sulfonylurea, your provider will review your regimen before starting.

Oral contraceptives + tirzepatide: Tirzepatide can lower the effectiveness of oral hormonal birth control during initiation and for 4 weeks after each dose increase. Use a non-oral method or add a barrier method during these windows. Semaglutide does not carry this interaction.

Time-sensitive medications: Warfarin, certain antibiotics, and some pain medications can be affected by slowed gastric emptying, particularly when starting tirzepatide. Take these as prescribed and discuss monitoring with your provider.

Over-the-counter medicines:

• Ibuprofen (Advil) and antacids: These can be taken as needed alongside a GLP-1. If headaches keep coming back or get worse, contact us, because that may be a separate concern.
• Cold and flu medicine (such as Robitussin, NyQuil, and Sudafed): No common over-the-counter cold medicine ingredient is known to be a problem with a GLP-1 on its own. Formulations vary from brand to brand, and what is safe also depends on your other medications and health conditions, so check with your pharmacist or doctor about the specific product. While you are sick, focus on fluids and electrolytes.
• Prescription pain medication after an injury or procedure: If your doctor has prescribed pain medication, take it as directed and tell them you take a GLP-1. Pain medication can add to constipation, which a GLP-1 can also cause.

Antibiotics and steroids: GLP-1 medications have very few known interactions with antibiotics or steroid pills. If you start either one, message your care team so your provider can review the combination and your plan. You can keep monitoring how you feel and contact us if side effects increase.

Prednisone and your progress: Prednisone can increase appetite, cause fluid retention, and temporarily slow weight loss. These effects are expected and are not a sign that your injections have stopped working.

If another doctor changes a medicine: If a medicine you take is increased, reduced, or switched by another prescriber, let your care team know. Your Belle provider will review your current dose and recent labs and tell you whether any change is needed. Please do not adjust your GLP-1 dose on your own.

Medicines that depend on careful absorption: Some medicines, such as levodopa for Parkinson's disease, need to be absorbed well in the intestines. If you take a medicine like this, message your care team before you start so your provider can decide your starting dose, and keep your specialist updated. Do not change when or how you take your other medicine unless that doctor tells you to.

Most common medications including PPIs, statins, SSRIs, and blood pressure medicines don't need dose changes when starting a GLP-1. Your provider may want to monitor more closely during initiation.

Examples of medicines that can be taken with a GLP-1: Our clinicians have confirmed there is no known interaction between GLP-1 medications such as tirzepatide and:

• Antidepressants and other psychiatric medications, such as Lexapro and Latuda
• Statins, such as Crestor (rosuvastatin). If you take a statin, tell us about any muscle pain or weakness, severe abdominal pain, or nausea that does not go away.
• Thyroid medication, such as NP Thyroid. Keep both your Belle team and your primary care provider updated.
• Estradiol for menopause. This is different from oral birth control pills, which are covered above.

If your medicine is not on this list, that does not mean it is a problem. GLP-1 medications have very few drug interactions, but tell your care team about every medicine you take so your provider can review it.

Using more than one Belle treatment: Tirzepatide, GLOW blend, NAD+, and glutathione can be used together. There is no set limit on how many peptides you can use. Safety depends on the specific medications, the doses, how each one is given, and your overall health, so tell your care team about everything you take and they will review your plan.

Always share your full medication list with your Belle provider and any other prescribers.

Supplements and vitamins: For questions about berberine, B12, B6, multivitamins, and other supplements, see "Can I take supplements and vitamins with my GLP-1, and will it affect my blood work?"