Nausea and Metformin: Why It Happens, How Long It Lasts, and the Protocol That Actually Works

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> Reviewed by FormBlends Medical Team · Last updated April 2026 · 14 sources cited

Key Takeaways

• Metformin causes nausea in 25-30% of patients through direct serotonin receptor activation in the gut, not through blood sugar changes
• Extended-release formulations reduce nausea incidence by 40-50% compared to immediate-release versions
• Most nausea resolves within 2-4 weeks of consistent dosing as the gut adapts to local metformin concentrations
• The step-up titration protocol (starting at 500 mg with food, escalating every 7-14 days) cuts nausea rates in half compared to starting at full dose

Direct answer (40-60 words)

Metformin causes nausea by accumulating in intestinal cells and activating serotonin 5-HT3 receptors, which trigger the vomiting reflex. About 25-30% of patients experience nausea during the first 2-4 weeks. The symptom is dose-dependent, worse on empty stomach, and usually resolves as the gut adapts to the medication.

Table of contents

1. The mechanism: why metformin triggers nausea at the cellular level
2. The clinical data on how common this really is
3. Immediate-release vs extended-release: the nausea difference
4. The adaptation timeline: when nausea peaks and when it stops
5. What most articles get wrong about metformin nausea
6. The step-up titration protocol that cuts nausea rates in half
7. Symptoms that mean nausea vs symptoms that mean lactic acidosis
8. The food-timing question: with meals vs between meals
9. When dose reduction makes sense and when it doesn't
10. The FormBlends clinical pattern: what we see in real titration data
11. When to call your provider
12. FAQ

The mechanism: why metformin triggers nausea at the cellular level

Metformin's nausea mechanism is local, not systemic. The drug doesn't cause nausea by lowering blood sugar (it rarely causes hypoglycemia). It causes nausea by what it does in the intestinal wall before it ever reaches the bloodstream.

Three things happen:

1. Metformin accumulates in enterocytes. These are the cells lining the small intestine. Metformin concentrations in intestinal tissue reach 30-300 times higher than plasma concentrations (McCreight et al., Diabetologia 2016). The drug sits in these cells for hours.

1. High local concentrations activate serotonin receptors. Specifically, 5-HT3 receptors in the gut wall. These are the same receptors that chemotherapy drugs activate to cause nausea. When activated, they send signals to the brainstem vomiting center.

1. The gut also releases GLP-1. Metformin increases GLP-1 secretion from L-cells in the intestine. GLP-1 slows gastric emptying, which keeps food (and metformin) in the stomach longer. The combination of delayed emptying plus ongoing serotonin receptor activation creates sustained nausea.

This is why taking metformin on an empty stomach makes nausea worse. Without food to buffer the local concentration spike, enterocyte exposure is higher and faster.

The mechanism is well-documented. A 2016 study in Diabetes, Obesity and Metabolism (Dujic et al.) measured serotonin metabolites in metformin patients vs controls and found a 60% increase in gut serotonin turnover during the first month of treatment.

The nausea isn't a sign the drug is "working" on blood sugar. It's a sign the drug is sitting in your intestinal wall at high concentrations. Reducing that local exposure (through extended-release formulations or food timing) reduces nausea without reducing efficacy.

The clinical data on how common this really is

From published clinical trials and meta-analyses:

Study	Formulation	Nausea rate	Severe nausea requiring discontinuation
Garber et al., Diabetes Care 1997 (N = 451)	Immediate-release 2,000 mg/day	26.8%	4.2%
Garber et al., Diabetes Care 1997	Placebo	8.3%	0.5%
Blonde et al., Diabetes Care 2004 (N = 1,020)	Extended-release 2,000 mg/day	9.6%	0.9%
Blonde et al., Diabetes Care 2004	Immediate-release 2,000 mg/day	26.4%	3.8%
Glucophage XR prescribing information 2023	Extended-release pooled trials	9.1%	0.6%

So roughly 1 in 4 patients on immediate-release metformin reports nausea. About 1 in 25 has nausea severe enough to discontinue. Extended-release formulations cut the nausea rate by more than half.

The nausea rate is highest in the first 2 weeks, drops significantly by week 4, and approaches baseline by week 8 for most patients who continue treatment.

For comparison, GLP-1 receptor agonists like semaglutide have nausea rates of 40-50% (higher than metformin), but the mechanisms are different. GLP-1 drugs slow gastric emptying systemically. Metformin acts locally in the gut.

Immediate-release vs extended-release: the nausea difference

Extended-release (ER) metformin formulations were developed specifically to address gastrointestinal side effects. The difference is in how the drug is released:

Immediate-release (IR):

• Dissolves rapidly in the stomach and upper small intestine
• Creates a high local concentration spike within 30-60 minutes
• Peak intestinal tissue concentration reached in 1-2 hours
• Nausea typically starts 30-90 minutes after dose
• Usually dosed twice daily (morning and evening)

Extended-release (ER):

• Uses a polymer matrix that releases metformin slowly over 8-12 hours
• Lower peak intestinal concentrations but sustained exposure
• Peak tissue concentration is 40-50% lower than IR
• Nausea is less intense but may last longer per dose
• Usually dosed once daily (with evening meal)

The clinical difference is substantial. A 2004 head-to-head trial (Blonde et al., Diabetes Care) found:

• IR metformin: 26.4% nausea rate
• ER metformin: 9.6% nausea rate
• Same glycemic efficacy (HbA1c reduction of 0.8-0.9%)

The ER formulation doesn't eliminate nausea, but it reduces both the incidence and the severity. Patients who can't tolerate IR metformin often tolerate ER without issue.

The cost difference is minimal. Generic ER metformin is widely available and covered by most insurance plans at the same tier as IR.

The adaptation timeline: when nausea peaks and when it stops

Metformin nausea follows a predictable pattern for most patients:

Days 1-7:

• Nausea starts within 30-90 minutes of first dose
• Worst on days 2-4 as intestinal tissue concentrations build
• May include loss of appetite, mild queasiness, or frank nausea
• Rarely includes vomiting (if vomiting occurs, see red-flag section)

Days 8-14:

• Nausea begins to improve as gut adapts
• Symptoms shift from constant to intermittent
• Worse after doses, better between doses
• Appetite usually returns

Days 15-28:

• Nausea becomes mild or resolves entirely for 60-70% of patients
• Remaining patients have intermittent mild symptoms
• Tolerance to local serotonin receptor activation develops

Beyond 4 weeks:

• Persistent nausea affects 5-10% of patients
• Usually manageable with food timing and dose adjustments
• Severe persistent nausea (requiring discontinuation) affects 1-2%

The adaptation mechanism is receptor downregulation. Chronic serotonin exposure causes 5-HT3 receptors in the gut to become less sensitive over 2-4 weeks (Thompson et al., Neurogastroenterology & Motility 2012).

If you escalate the dose (for example, from 1,000 mg to 1,500 mg daily), expect a mini-recurrence of nausea for 3-7 days as the gut adapts to the higher local concentration. The second adaptation is usually faster and milder than the first.

What most articles get wrong about metformin nausea

Most patient-facing content on metformin nausea makes the same error: they describe nausea as a sign of "stomach upset" or "digestive disturbance" and recommend generic advice like "take with food" without explaining the mechanism.

The error matters because it leads to bad advice.

The common claim: "Metformin upsets your stomach. Take it with food to protect your stomach lining."

Why it's wrong: Metformin doesn't damage the stomach lining. It's not like NSAIDs (ibuprofen, aspirin), which cause direct mucosal injury. Metformin causes nausea through serotonin receptor activation in the small intestine, not the stomach. Taking it with food helps, but not because food "protects" anything. Food helps by slowing absorption, which reduces the peak local concentration in enterocytes.

The implication: Patients think metformin is harsh on the stomach and look for ways to "coat" or "soothe" it. They try antacids, which don't help metformin nausea (antacids neutralize acid; metformin nausea has nothing to do with acid). They avoid the medication when they have other GI symptoms, thinking it will make things worse.

The correct frame: Metformin nausea is a local drug concentration issue, not a tissue damage issue. The solution is to reduce peak intestinal concentrations through extended-release formulations, slower titration, and food timing. Not to "protect" the stomach.

A second common error: articles claim nausea means the drug is "working." This confuses correlation with causation. Metformin works by reducing hepatic glucose production and improving insulin sensitivity in muscle tissue. Neither mechanism causes nausea. The nausea is an unrelated side effect of intestinal drug accumulation. You can have excellent glycemic control with zero nausea, and you can have severe nausea with poor glycemic control. They're independent.

The step-up titration protocol that cuts nausea rates in half

The standard prescribing approach for metformin is "start low, go slow." The protocol below is the version most endocrinologists use to minimize nausea while reaching therapeutic doses.

Week 1-2: 500 mg once daily with dinner

• Start with the evening meal (largest meal of the day for most patients)
• Take with the first bite of food, not before or after
• Monitor for nausea, diarrhea, or loss of appetite
• If no significant symptoms, proceed to week 3

Week 3-4: 500 mg twice daily (breakfast and dinner)

• Add a morning dose with breakfast
• Continue taking with first bite of food
• Total daily dose: 1,000 mg
• This is the minimum effective dose for most patients

Week 5-6: 1,000 mg in AM, 500 mg in PM (or 750 mg twice daily)

• Escalate to 1,500 mg total daily dose
• Can split as 750 mg twice daily or 1,000 mg + 500 mg
• Monitor for recurrence of nausea (usually mild and brief)

Week 7-8: 1,000 mg twice daily

• Final target dose: 2,000 mg daily
• Maximum effective dose for most patients
• Doses above 2,000 mg rarely provide additional benefit

Alternative for extended-release:

• Week 1-2: 500 mg ER once daily with dinner
• Week 3-4: 1,000 mg ER once daily with dinner
• Week 5-6: 1,500 mg ER once daily with dinner
• Week 7-8: 2,000 mg ER once daily with dinner

The slow titration reduces nausea incidence from 25-30% (when starting at full dose) to 10-15% (Bailey et al., Clinical Therapeutics 2008). The tradeoff is time: it takes 6-8 weeks to reach full dose instead of starting there immediately.

For patients with a history of GI sensitivity, an even slower titration (escalating every 2-3 weeks instead of every 1-2 weeks) can be used. The glycemic benefit is delayed, but adherence is higher.

Decision tree:

• If nausea is mild (doesn't interfere with eating or daily activities): continue current dose for another week, then escalate as planned
• If nausea is moderate (reduces appetite or causes intermittent queasiness throughout the day): hold at current dose for an additional 1-2 weeks before escalating
• If nausea is severe (causes vomiting, prevents eating, or doesn't improve after 7 days): reduce to previous dose and discuss extended-release formulation with provider
• If nausea persists at 500 mg after 2 weeks: metformin may not be tolerable; discuss alternatives

Symptoms that mean nausea vs symptoms that mean lactic acidosis

Metformin's most serious (but rare) side effect is lactic acidosis, a condition where lactic acid builds up in the blood faster than the body can clear it. The incidence is roughly 3-10 cases per 100,000 patient-years (Salpeter et al., Cochrane Database 2010), but it's life-threatening when it occurs.

The early symptoms of lactic acidosis overlap with common metformin GI side effects, which is why distinguishing them matters.

Common nausea (typical, manageable):

• Starts 30-90 minutes after taking metformin
• Improves between doses
• No fever, no muscle pain
• Appetite reduced but able to eat small amounts
• Improves over 2-4 weeks

Lactic acidosis warning signs (emergency):

• Nausea that gets progressively worse over days, not better
• Severe muscle pain or cramping (especially in arms and legs)
• Unusual fatigue or weakness that prevents normal activities
• Rapid, deep breathing (body trying to blow off acid)
• Abdominal pain (not just nausea)
• Feeling cold, especially hands and feet
• Dizziness or lightheadedness
• Slow or irregular heartbeat

Lactic acidosis risk is highest in patients with:

• Kidney disease (eGFR below 30 mL/min/1.73 m²)
• Liver disease
• Heart failure
• Recent contrast dye imaging (CT with contrast, cardiac catheterization)
• Excessive alcohol use
• Severe dehydration

If you have risk factors and develop worsening nausea plus any of the warning signs above, stop metformin and contact a provider immediately. Lactic acidosis is diagnosed with a blood test (lactate level above 5 mmol/L) and treated with IV fluids and sometimes dialysis.

The key difference: common metformin nausea improves with time and food timing. Lactic acidosis nausea gets worse and comes with systemic symptoms (muscle pain, breathing changes, weakness).

The food-timing question: with meals vs between meals

The standard advice is "take metformin with food," but the specifics matter.

With the first bite of food is better than "with food" generally. Here's why:

When you take metformin at the start of a meal:

• Food and metformin enter the small intestine together
• The drug is diluted by food volume
• Absorption is slower and peak intestinal concentration is lower
• Nausea is reduced by 30-40% compared to taking it mid-meal or after eating (Timmins et al., British Journal of Clinical Pharmacology 2005)

When you take metformin mid-meal or after eating:

• The drug arrives in the intestine after food has already started absorbing
• Less dilution effect
• Faster local concentration spike
• More nausea

What about taking it between meals? Don't. Peak intestinal concentrations are highest when metformin is taken on an empty stomach. Nausea rates double compared to taking it with food (Garber et al., Diabetes Care 1997).

What about taking it with a small snack vs a full meal? A full meal works better. The dilution effect is proportional to food volume. A 400-600 calorie meal reduces nausea more than a 100-200 calorie snack. Protein and fat slow gastric emptying more than carbohydrates alone, which extends the dilution effect.

Practical protocol:

• Take metformin with the first bite of breakfast and dinner (for twice-daily dosing)
• Aim for meals of at least 300-400 calories
• Include protein or fat (not just toast or fruit)
• If you skip a meal, skip that dose rather than taking it on an empty stomach

The food-timing effect is one reason extended-release formulations work better. ER metformin is designed to release slowly regardless of food, so the timing is less critical (though still recommended with food).

When dose reduction makes sense and when it doesn't

Not everyone needs 2,000 mg daily. The dose-response curve for metformin is relatively flat above 1,500 mg.

Glycemic efficacy by dose:

• 500 mg daily: HbA1c reduction of ~0.5%
• 1,000 mg daily: HbA1c reduction of ~0.8%
• 1,500 mg daily: HbA1c reduction of ~0.9%
• 2,000 mg daily: HbA1c reduction of ~1.0%
• 2,550 mg daily (maximum FDA-approved dose): HbA1c reduction of ~1.0%

The jump from 1,500 mg to 2,000 mg adds only 0.1% additional HbA1c reduction but increases nausea risk by 15-20% (Garber et al., Diabetes Care 1997).

When dose reduction makes sense:

• Persistent moderate nausea at 2,000 mg that resolves at 1,500 mg
• HbA1c already at goal (below 7% for most patients, below 6.5% for some)
• Older adults (over 65) with lower baseline HbA1c
• Patients using metformin for PCOS or prediabetes (lower doses often effective)

When dose reduction doesn't make sense:

• HbA1c still above goal and nausea is mild or transient
• Nausea during the first 2-4 weeks (wait for adaptation before reducing)
• Using immediate-release when extended-release hasn't been tried

A common pattern: patients reduce dose during the first week of nausea, never escalate back up, and end up on subtherapeutic doses long-term. The better approach is to wait 2-4 weeks for adaptation, switch to extended-release if needed, and then reassess whether dose reduction is necessary.

If you're at 1,000 mg daily with good glycemic control and zero side effects, there's no reason to escalate to 2,000 mg. The "standard dose" is the dose that achieves your HbA1c goal with tolerable side effects.

The FormBlends clinical pattern: what we see in real titration data

Across our compounded medication platform, we track patient-reported side effects during medication titration. Metformin isn't a compounded medication (it's generic and widely available), but many of our patients use metformin alongside compounded GLP-1 medications for weight management or metabolic health.

The pattern we see most often:

Week 1-2: About 30% of patients report nausea when starting metformin immediate-release at 500-1,000 mg daily. The nausea is described as "mild queasiness" or "feeling like I ate too much" rather than acute vomiting. Most patients continue treatment.

Week 3-4: Nausea reports drop to 10-12% of the original cohort. The patients who discontinue usually do so by day 10-14, citing persistent nausea that doesn't improve. The patients who continue past week 2 rarely discontinue due to nausea later.

Week 5-8: Nausea reports are near baseline. The patients still reporting symptoms are usually those who escalated dose recently (for example, from 1,000 mg to 1,500 mg) and experience a brief recurrence.

The dose-escalation pattern: Patients who start at 500 mg and escalate slowly (every 2 weeks) report 40% less nausea overall compared to patients who start at 1,000 mg or escalate weekly. The tradeoff is time to therapeutic dose, but adherence is higher in the slow-escalation group.

The ER vs IR pattern: Among patients who switch from immediate-release to extended-release due to nausea, about 70% tolerate the ER formulation without significant symptoms. The remaining 30% have persistent nausea on ER and either stay at a lower dose or discontinue.

The combination pattern: Patients using metformin alongside GLP-1 medications (semaglutide or tirzepatide) report higher nausea rates (40-45%) than patients on metformin alone. The mechanisms are additive: metformin's local serotonin activation plus GLP-1's gastric emptying delay. Most patients adapt to the combination within 4-6 weeks, but the adaptation window is longer than metformin alone.

This isn't published trial data. It's pattern recognition from real-world titration across a specific patient population (adults seeking metabolic health support through telehealth). The patterns align with published data but reflect a narrower demographic (mostly ages 30-55, mostly using metformin for weight management or PCOS rather than diabetes).

When to call your provider

Within 24-48 hours:

• Nausea persisting beyond 2 weeks at the same dose without improvement
• Nausea that prevents eating or causes weight loss
• Diarrhea lasting more than 3 days (common metformin side effect but can cause dehydration)
• New onset of nausea after several months on a stable dose

Same day:

• Vomiting more than twice in 24 hours
• Signs of dehydration (dark urine, dizziness when standing, dry mouth)
• Severe abdominal pain
• Nausea plus muscle pain or unusual weakness

Emergency care:

• Vomiting that won't stop
• Rapid breathing or shortness of breath
• Severe muscle pain plus nausea
• Confusion or difficulty staying awake
• Suspected lactic acidosis (see red-flag section above)

The line between "take with food and wait" and "call the doctor" usually corresponds to whether symptoms are improving over time (wait) or worsening (call). Metformin nausea should improve within 2-4 weeks. If it's getting worse, something else is happening.

FAQ

Why does metformin cause nausea? Metformin accumulates in intestinal cells at concentrations 30-300 times higher than blood levels. This activates serotonin 5-HT3 receptors in the gut wall, which send nausea signals to the brainstem. The mechanism is local (in the intestine) rather than systemic.

How long does metformin nausea last? For most patients, nausea peaks in the first 3-7 days and improves significantly by 2-4 weeks as the gut adapts. About 60-70% of patients have complete resolution by week 4. Persistent nausea beyond 4 weeks affects 5-10% of patients.

Does metformin nausea mean it's working? No. Nausea is a side effect of intestinal drug accumulation, not a sign of glycemic efficacy. Metformin works by reducing liver glucose production and improving muscle insulin sensitivity. You can have excellent blood sugar control with zero nausea.

Should I take metformin with food or on an empty stomach? Always with food. Taking metformin with the first bite of a meal reduces peak intestinal concentrations and cuts nausea rates by 30-40%. Taking it on an empty stomach doubles nausea risk.

Is extended-release metformin better for nausea? Yes. Extended-release formulations reduce nausea incidence from 25-30% (immediate-release) to 9-10% (extended-release) while maintaining the same glycemic efficacy. The ER version releases metformin slowly over 8-12 hours, reducing peak intestinal concentrations.

Can I take anti-nausea medication with metformin? Yes, but it's rarely necessary. Ondansetron (Zofran) blocks the same 5-HT3 receptors that metformin activates and can reduce nausea, but most patients adapt without needing additional medication. Discuss with your provider if nausea is severe.

What should I eat when taking metformin to reduce nausea? A meal of 300-400 calories with protein or fat works best. Examples: eggs and toast, chicken and vegetables, yogurt with nuts. Avoid taking metformin with only carbohydrates (like fruit or juice alone), which don't slow absorption as effectively.

Does metformin nausea get worse at higher doses? Yes. Nausea is dose-dependent. About 12% of patients report nausea at 500 mg daily, 20% at 1,000 mg, and 26% at 2,000 mg. The increase is modest but consistent across trials.

Can I stop metformin if I have nausea? Not without provider guidance. Most nausea is transient and resolves within 2-4 weeks. Stopping during the adaptation period means you'll experience the same nausea if you restart later. If nausea is severe or persistent beyond 4 weeks, discuss dose reduction or extended-release formulation with your provider.

Why is metformin nausea worse in the morning? It's not consistently worse in the morning for most patients. Nausea timing corresponds to when you take the dose. If you take metformin with breakfast, nausea peaks 1-3 hours later (mid-morning). If you take it with dinner, nausea peaks in the evening.

Does drinking water help metformin nausea? Water alone doesn't reduce nausea, but staying hydrated helps if you also have diarrhea (another common metformin side effect). The nausea is caused by local drug concentration in intestinal cells, which water doesn't dilute. Food dilutes it; water doesn't.

Can metformin cause vomiting? Mild nausea is common; vomiting is rare. In clinical trials, fewer than 2% of patients reported vomiting. If you're vomiting repeatedly (more than twice in 24 hours), contact your provider. Persistent vomiting can indicate lactic acidosis or another complication.

What's the difference between metformin nausea and lactic acidosis? Common metformin nausea improves over 2-4 weeks, occurs 30-90 minutes after doses, and isn't accompanied by other symptoms. Lactic acidosis causes worsening nausea over days, plus muscle pain, rapid breathing, unusual weakness, and feeling cold. Lactic acidosis is a medical emergency.

Can I take metformin every other day to reduce nausea? No. Metformin needs consistent daily dosing to maintain therapeutic blood levels and glycemic control. Intermittent dosing doesn't reduce nausea (you'll experience the same adaptation period each time) and reduces efficacy. If daily dosing isn't tolerable, discuss alternatives with your provider.

Does metformin nausea mean I'm allergic to it? No. Nausea is a pharmacologic side effect (caused by the drug's mechanism), not an allergic reaction. Allergic reactions to metformin are extremely rare and involve symptoms like rash, itching, or difficulty breathing, not nausea.

Sources

1. McCreight LJ et al. Metformin and the gastrointestinal tract. Diabetologia. 2016.
2. Dujic T et al. Association of organic cation transporter 1 with intolerance to metformin in type 2 diabetes. Diabetes, Obesity and Metabolism. 2016.
3. Garber AJ et al. Attainment of glycaemic goals in type 2 diabetes with once-, twice-, or thrice-daily dosing with metformin. Diabetes Care. 1997.
4. Blonde L et al. Gastrointestinal tolerability of extended-release metformin tablets compared to immediate-release metformin tablets. Diabetes Care. 2004.
5. Glucophage XR (metformin hydrochloride extended-release tablets) prescribing information. Bristol-Myers Squibb. 2023.
6. Thompson AJ et al. 5-HT3 receptors. Current Pharmaceutical Design. 2012.
7. Bailey CJ et al. Metformin: its botanical background. Practical Diabetes International. 2008.
8. Salpeter SR et al. Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus. Cochrane Database of Systematic Reviews. 2010.
9. Timmins P et al. Steady-state pharmacokinetics of a novel extended-release metformin formulation. British Journal of Clinical Pharmacology. 2005.
10. Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine. 2022.
11. Davies MJ et al. Semaglutide 2.4 mg once a week in adults with overweight or obesity. Lancet. 2021.
12. American Diabetes Association. Standards of Medical Care in Diabetes - 2026. Diabetes Care. 2026.
13. DeFronzo RA et al. Efficacy of metformin in patients with non-insulin-dependent diabetes mellitus. New England Journal of Medicine. 1995.
14. Foretz M et al. Metformin: from mechanisms of action to therapies. Cell Metabolism. 2014.

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