Dermal fillers and botox: how they work and what to ask

Injectable treatments for lines and facial volume are among the most widely discussed cosmetic procedures. Two of them are often mentioned together: botulinum toxin injections, commonly called “botox”, and dermal fillers. They are both given with a needle and neither involves surgery, but they work in quite different ways and carry different risks. This guide explains what each one does, what to expect, which warning signs need attention and which questions to ask before you agree to treatment.

Botulinum toxin is a substance made by the bacterium Clostridium botulinum. When small amounts are injected into a muscle, it blocks the chemical messenger that tells the muscle to contract. The muscle is temporarily weakened, so lines created by repeated movement soften. Over time the nerve endings regrow and the muscle recovers, which is why the effect is not permanent.

Dermal fillers, sometimes called soft tissue fillers or injectable implants, are medical devices injected under the skin. Rather than relaxing a muscle, they physically fill a fold or add fullness. Some are made from materials such as hyaluronic acid that the body gradually absorbs; others are designed to be permanent. Because they act so differently, it helps to think of botulinum toxin as a treatment for movement and fillers as a treatment for volume and folds.

What botulinum toxin injections are used for

The British Association of Aesthetic Plastic Surgeons (BAAPS) describes cosmetic botulinum toxin as a treatment for wrinkles caused by muscle movement, such as frown lines between the eyebrows, horizontal forehead lines and crow’s feet around the eyes. It is also used to treat excessive sweating of the armpits and palms, which is a separate medical use.

The injections are given with a very small needle, usually at several points in the target muscles. Sedation or local anaesthetic is generally not needed, and most people can carry on with normal activities straight away. According to BAAPS, the effect usually begins 24 to 72 hours after treatment and is at its strongest at around 1 to 2 weeks.

BAAPS and the American Academy of Dermatology (AAD) both describe the effect on lines as lasting about 3 to 4 months, and the AAD notes it can sometimes last longer. When it wears off, the treatment can be repeated. There are limits to what it can do: BAAPS explains that it does not treat lines from sun damage or from sagging skin, very deep lines may need repeated treatment, and it can exaggerate an existing difference between the two sides of the face.

What dermal fillers are used for

The U.S. Food and Drug Administration (FDA) explains that fillers are used to smooth moderate to severe facial wrinkles and folds, such as the lines running from the nose to the corners of the mouth, and to add volume to the lips, cheeks, chin and back of the hands.

How long a filler lasts depends on the material, the area injected, the amount used and the tissue underneath. Fillers that the body absorbs may need repeat treatment to keep the effect. The FDA points out that permanent fillers, and fillers not made of hyaluronic acid, may be difficult or impossible to remove if side effects develop, which is worth weighing up before choosing a product.

The FDA also lists uses it has not approved, including injecting filler to enlarge the breasts, buttocks or feet, and injecting certain areas such as the nose, forehead, neck or around the eyes. It warns that injectable silicone is not approved for any cosmetic use, that needle-free injection devices are not approved for fillers and that fillers should not be bought online or self-injected.

Side effects and rare complications

Most side effects of botulinum toxin are mild and temporary. The AAD lists swelling, redness, soreness and bruising at the injection sites, with bruising typically lasting about a week. A mild headache is uncommon. Occasionally a nearby muscle is affected, causing a temporarily drooping brow or eyelid; BAAPS notes this usually improves as the treatment wears off. Very rarely, the AAD says, signs of botulism such as trouble breathing, swallowing or speaking can occur.

With fillers, the FDA describes common side effects as bruising, redness, swelling, pain, tenderness, itching and rash. Most appear soon after the injection and settle within days to weeks, although some effects can appear weeks, months or even years later. Less common problems include lumps or nodules, infection and allergic reactions.

The most serious concern with fillers is accidental injection into a blood vessel. The FDA explains that this can block blood flow and lead to tissue damage, vision problems including blindness, or stroke, and that these complications can be permanent. This is one reason the person injecting you needs detailed knowledge of facial anatomy and a plan for dealing with complications.

Who may not be suitable

BAAPS advises against botulinum toxin for people with neuromuscular disorders such as myasthenia gravis, people taking certain muscle relaxants or certain antibiotics, people who are pregnant or breastfeeding, people with infection or inflammation where the injection would go and people with bleeding disorders.

For fillers, the FDA advises telling your practitioner if you have active skin inflammation or infection, a bleeding disorder, severe allergies or a history of anaphylaxis, or allergies to any of the filler’s ingredients. It notes that safety has not been established in pregnancy or breastfeeding, in people prone to raised or thickened scars, or when fillers are combined with muscle-relaxing injections. A good consultation covers your medical history, medicines and any previous treatments before anything is injected.

Rules on who can treat you

Rules on who can have these treatments, who can give them and whether a prescription is needed vary from country to country, so it helps to know how they apply where you are being treated. Your doctor will explain how they apply in Türkiye.

In Türkiye, the Ministry of Health regulation on private outpatient health facilities, published in the Official Gazette in April 2025, allows medical centres, polyclinics and doctors’ private practices to offer cosmetic health services. These services must be provided by physicians, within the skills they have gained through their training curriculum or a certificate, and only where the facility has the required examination room and equipment and is permitted to carry out the procedure.

Wherever you are treated, the NHS suggests asking for the name of the product, where it came from and what training the practitioner has, and it advises avoiding practitioners who have only completed a short course.

The NHS also lists warning signs to avoid, including treatments offered at group events where alcohol is served, vouchers bought from discount websites, mobile services in homes or hotels and practitioners who advertise only on social media. The AAD similarly advises never having injections at a party, salon or someone’s home.

Questions to ask before treatment

The NHS recommends booking a consultation with the person who will treat you, not paying until you have had one, and taking time to decide afterwards. You can ask for written information, such as the product leaflet, to read at home. Useful questions include:

• What are your qualifications and training, and how many of these treatments have you carried out?
• Do you belong to a relevant professional association or an accredited register?
• Who will give the injections, and who provides the aftercare?
• Which product will you use, and where was it sourced?
• What results are realistic for me, and how long are they likely to last?
• What are the common complications, and what would you do if something went wrong?
• What aftercare is included, and who do I contact if I am worried afterwards?
• Do you have insurance that covers treating complications?

If you have ongoing health conditions or take regular medicines, bring a list so these can be checked against the treatment you are considering.

Aftercare and when to seek help

After botulinum toxin injections, the AAD advises not rubbing or massaging the treated areas, applying make-up gently and waiting two hours before strenuous activity such as heavy lifting or a workout. Your practitioner will give specific instructions for your treatment, including when to return for a review.

After filler treatment, the FDA advises seeking immediate medical care if you notice unusual pain, changes in your vision, white, grey or blue skin near the injection site, or signs of a stroke such as difficulty speaking, a drooping face, weakness or confusion. Signs such as difficulty swallowing or breathing, slurred speech, double or blurred vision or drooping eyelids can point to botulism; the CDC describes botulism as a medical emergency and advises seeing a doctor or going to an emergency department straight away.

Next steps

If you are considering injectable treatments, a consultation with a qualified practitioner is the place to discuss your goals, your medical history and whether botulinum toxin, fillers or neither is right for you. You can read about our plastic and aesthetic surgery specialists, see the dermal filler and botulinum toxin package, or answer a few questions to be matched with a doctor: Find my physician.