Lip Flip Side Effects: What's Normal, What's Temporary, and What's Rare
The lip flip is one of the lowest-risk cosmetic treatments available. It uses a small number of Botox or Dysport units in a single area, takes under five minutes, and requires no downtime. But “low risk” doesn’t mean “no side effects,” and patients considering the treatment deserve a complete picture of what might happen — not just a reassurance that everything will be fine.
This post covers every side effect associated with the lip flip, organized by how likely you are to experience it. Most are mild, temporary, and resolve on their own within days. A few are functional — meaning they affect how your lips work rather than how they look. And a small number are technique-dependent, meaning they’re more likely to occur with inexperienced injectors or incorrect dosing. Understanding the full profile helps you prepare realistically and recognize what’s normal during your recovery.
Common Side Effects (Most Patients)
These are the expected, predictable consequences of injecting a neuromodulator into facial muscle tissue. They’re not complications — they’re the normal aftermath of the procedure.
Minor Bruising at Injection Sites
The lip flip involves 4–6 small injection points along the upper lip border. Each point creates a micro-puncture in tissue that has a dense capillary network. Minor bruising at one or more injection sites is common, appearing as small purple or reddish dots within the first 24 hours.
Lip flip bruising is typically milder than lip filler bruising because the injection is shallower and the volume of product entering the tissue is far smaller. Most lip flip bruises are pinpoint-sized — easily concealed with makeup — and resolve within 2–4 days. Deeper bruising is uncommon but possible if a slightly larger vessel is nicked.
To discuss bruising risk, give your injector a complete list of medicines and supplements before treatment. Do not stop, restart, or change prescribed aspirin, anticoagulants, or other medicines for a cosmetic appointment unless the clinician who prescribes them tells you to. Your injector and prescribing clinician can decide whether any adjustment is appropriate. Read the NHS guidance on anticoagulant medicines.
Mild Tenderness
The injection sites may feel slightly sore or sensitive to the touch for 1–2 days. This is standard needle-trauma soreness — the same sensation you’d feel after any injection. It doesn’t require pain medication and resolves on its own. Unlike lip filler, which produces persistent tenderness for several days as the tissue accommodates new volume, lip flip tenderness is brief because no volumetric material is placed in the tissue.
Slight Swelling
A small amount of swelling around the injection sites is possible in the first 24 hours, but it’s minimal compared to the swelling associated with lip filler. The lip flip doesn’t displace tissue or inject volume, so the inflammatory response is proportionally smaller. Most patients don’t notice visible swelling; those who do describe it as a very mild puffiness that resolves within a day.
Functional Side Effects (Temporary, Related to Muscle Relaxation)
This is the category that distinguishes the lip flip from other Botox treatments. Because the orbicularis oris controls fundamental mouth functions — speaking, eating, drinking, forming certain sounds — relaxing it has functional consequences that go beyond the cosmetic effect. These are temporary and resolve as the neurotoxin wears off, but they’re worth understanding before treatment.
Difficulty Drinking Through a Straw
This is the most commonly reported functional side effect and the one patients are least prepared for. Drinking through a straw requires the orbicularis oris to create a seal and generate suction. When the muscle is partially relaxed by the lip flip, the seal is weaker and you may find that liquid dribbles or that creating the necessary suction takes more effort.
The severity depends on the dose and your individual muscle response. At the standard lip flip dose, most patients can still use a straw — it just feels slightly different, like the seal isn’t as tight. At higher doses (or in patients who are particularly sensitive to the neurotoxin), straw use may be genuinely awkward for the first 1–2 weeks until the body adjusts.
This is temporary. As the Botox gradually wears off over the following weeks, full straw function returns. In the meantime, drinking directly from a glass or cup is the simple workaround.
Subtle Changes in Speech or Pronunciation
Certain sounds — particularly those that require tight lip closure or active lip rounding (B, M, P, W, and certain vowel shapes) — may feel slightly different in the first few days after a lip flip. Most patients don’t experience a noticeable speech change at standard doses, but patients whose work depends on precise articulation (singers, public speakers, broadcasters, wind instrument players) should be aware that a subtle shift is possible.
This doesn’t mean the lip flip causes a lisp or dramatically alters how you sound. It means that the lip closure pattern is slightly softer than your pre-treatment baseline, which can be perceptible to the patient even if it’s inaudible to others. The effect is most noticeable in the first week and diminishes as you adapt.
Difficulty Whistling
Whistling requires precise tension in the orbicularis oris — the exact tension the lip flip is designed to reduce. Most lip flip patients find they cannot whistle effectively for the duration of the treatment effect. This is a predictable consequence of the mechanism and not a sign that something went wrong. If whistling is a significant part of your daily life or profession, mention it to your injector during the consultation.
Mild Lip Fatigue or “Heaviness”
Some patients describe a feeling of heaviness or fatigue in the upper lip during the first week — as if the lip is slightly tired or sluggish. This is the subjective sensation of reduced muscle tone. Your brain is accustomed to the lip having a certain resting tension, and when that tension decreases, the area can feel different in a way that’s hard to articulate beyond “heavy” or “weird.”
This sensation typically resolves within 5–7 days as your nervous system adapts to the new muscle tone. It doesn’t indicate that the dose was too high or that the treatment was performed incorrectly. It’s the normal adjustment period as the neurotoxin takes full effect.
Temporary Difficulty with Certain Eating Motions
Biting into food that requires the upper lip to grip or tear — a large sandwich, an apple, corn on the cob — may feel slightly awkward in the first few days. The upper lip has less muscular control than usual and doesn’t press against food as firmly. This is a minor inconvenience rather than a significant limitation, and most patients adapt quickly by adjusting how they position food when biting.
Uncommon Side Effects (Small Percentage of Patients)
These occur infrequently and are typically related to dosing, injection placement, or individual sensitivity.
Asymmetric Relaxation
If the neurotoxin diffuses unevenly or if slightly more product is absorbed on one side, the upper lip may relax asymmetrically — one side flipping outward more than the other. This can create a subtle lopsided appearance or an uneven smile.
Mild asymmetry in the first few days is normal, as the Botox may take effect at different rates on each side. By day 10–14, the effect should be symmetric. If persistent asymmetry remains after two weeks, your injector at ELLEMES can assess whether a small touch-up on the undertreated side would correct the imbalance. This is a minor adjustment, not a redo of the entire treatment.
Over-Relaxation (Dose Too High)
If too many units are placed — either because the initial dose was too aggressive or because the product diffused more broadly than intended — the orbicularis oris can become overly relaxed. Symptoms of over-relaxation include noticeable difficulty closing the lips fully, inability to purse the lips, drooling during sleep, significant difficulty with straws and certain foods, and a “slack” appearance to the upper lip that looks more like muscle weakness than an intentional cosmetic effect.
Over-relaxation is uncomfortable and cosmetically undesirable, but it is not dangerous and it is fully temporary. The effect resolves as the Botox wears off — typically within 2–4 weeks for the most pronounced symptoms and 6–8 weeks for complete recovery. There is no antidote for Botox the way hyaluronidase dissolves filler; you have to wait for it to metabolize naturally.
This is the primary reason experienced injectors use conservative dosing for the lip flip. The margin between “effective” and “too much” is narrower around the mouth than in the forehead or crow’s feet. At ELLEMES, your injector starts at the lower end of the dosing range and adjusts based on how you respond, rather than maximizing the dose on the first treatment.
Headache
A mild headache following any Botox injection is possible, though it’s more commonly associated with forehead and glabellar (between the brows) treatment than with the lip flip specifically. If it occurs, it typically resolves within 24–48 hours and responds to standard over-the-counter medication. The mechanism isn’t fully understood — it may be related to needle trauma, temporary muscle tension changes, or the injection process itself rather than the neurotoxin.
Cold Sore Reactivation
As with any injection in or around the lips, patients with a history of HSV-1 (oral herpes / cold sores) may experience a reactivation triggered by the needle trauma. The risk is lower with the lip flip than with lip filler because fewer injection points are involved and the tissue disruption is less extensive, but it’s still possible. If you have a cold sore history — even infrequent outbreaks — inform your injector before treatment. Prophylactic antiviral medication (valacyclovir) can be prescribed to minimize the risk.
What the Lip Flip Won’t Cause
Online forums and social media generate a significant amount of anxiety around Botox side effects that either don’t apply to the lip flip specifically or are not realistic concerns at the doses used.
It won’t cause your lip to “freeze.” The lip flip uses 4–8 units — a small fraction of the total dose needed to immobilize a muscle. The orbicularis oris is not paralyzed; it’s mildly relaxed. You retain full ability to smile, talk, eat, and make facial expressions. The muscle function is reduced, not eliminated.
It won’t cause permanent muscle damage. Botox produces a temporary blockade of the neuromuscular junction. When the effect wears off — which it will, completely, within 2–3 months — the muscle returns to its full pre-treatment function. There is no cumulative damage from repeated treatments. Patients who’ve maintained lip flips for years can stop at any time and their lip function returns to exactly what it was before they started.
It won’t cause the lip to “droop” permanently. A temporary feeling of heaviness or softness is normal in the first week. This is not atrophy, and it’s not drooping. The lip’s resting position changes slightly because the muscle pulling it inward is relaxed — that’s the intended effect. When the Botox wears off, the muscle regains its full tone and the lip returns to its natural position.
It won’t spread to other parts of the face. At the doses used for a lip flip, the neurotoxin stays localized to the injection area. It does not migrate to distant muscles or cause systemic effects. The concern about Botox “spreading” applies to scenarios involving very large doses in patients with certain neuromuscular conditions — not to a 4–8 unit lip flip in a healthy patient.
How to Minimize Side Effects
Before treatment: Review your medication list with your injector; medication changes require the prescribing clinician’s guidance. Disclose cold sore history. Mention upcoming events that require precise speech or lip function so your injector can discuss treatment timing and possible temporary effects.
After treatment: Don’t press, rub, or massage the treatment area for 4 hours. Stay upright for at least 2 hours. Avoid strenuous exercise for 24 hours. Don’t manipulate the lip — touching the area can theoretically cause the neurotoxin to diffuse beyond the intended injection site. Follow the full aftercare instructions provided at your appointment.
First-time patients: If you’ve never had a lip flip before, your injector will likely start at a conservative dose. It’s better to experience a subtler-than-expected result and add units at a follow-up than to overshoot on the first treatment and deal with functional side effects that you have to wait out. The lip flip is one of the treatments where “less is more” is genuinely good practice.
When to Contact Your Provider
The vast majority of lip flip side effects are self-limiting and resolve within 1–2 weeks. However, contact your provider at ELLEMES if you experience any of the following: persistent or worsening asymmetry after two weeks, significant difficulty closing the mouth or controlling saliva, signs of infection at any injection site (increasing redness, warmth, swelling, or pus), or any reaction you find concerning. The functional effects described in this post — straw difficulty, mild speech changes, lip heaviness — are expected and temporary, but your provider can confirm whether what you’re experiencing falls within the normal range.
For the complete swelling and recovery timeline for lip filler (which has a different and more extensive recovery profile), see our post on lip filler swelling stages.
Learn more about the Lip Flip at ELLEMES Medical Spa →
ELLEMES Medical Spa is located at 5505 Peachtree Dunwoody Road in Sandy Springs, GA — serving patients from Buckhead, Brookhaven, Dunwoody, and greater Atlanta.