Your question actually provides an excellent segue into a discussion of several phenomena associated with Botox injection of the forehead that are completely unknown to most Botox patients. The first is that Botox is actually used clinically to prevent the onset of migraine headaches, and can be quite effective for this indication for a significant segment of patients who suffer from migraine headaches. However, in approximately 5% of these patients, unfortunately, the Botox itself can actually trigger the onset of a migraine headache.The second important point to be made is that some physicians, in an effort to minimize the pain their patients experience from injection of the forehead with Botox, will apply different combinations of topical anesthetics for varying periods of time, prior to the injection. Some of the medications in these topical anesthetic mixtures can themselves induce headaches.It is probably the case that some of the physicians who see the need to apply topical anesthesia prior to injection of the forehead with Botox are injecting the Botox in too deep a plane, causing the sharp tip of the needle to strike the periosteum of the frontal bone. Repeated sticks of the frontal bone can also cause headaches in some patients. The frontalis muscle, i.e., the muscle underlying the forehead skin, is actually a very thin muscle, and Botox can be injected very superficially just above this muscle and achieve its full clinical effect. There is no additional clinical efficacy achieved by injection Botox at the level of the periosteum. Indeed, it is more likely that a greater dose of Botox is required when injecting in a periosteal plane to achieve the same clinical efficacy of Botox injected above the frontalis muscle.You also state in your query that your forehead feels very heavy and that your right eye feels "achy and heavy" as well. A very common mistake made with injection of Botox in the forehead, especially in older patients who may already have some preexisting degree of brow or eyelid ptosis, is to inject dosages of botox into the forehead that are too great, or to place those injections too low in the forehead, either just below, or just above the eyebrow, as well as in a plane that is too deep, sometimes even at the level of the levator oculi muscle, the muscle that is responsible for allowing a patient to raise his upper eyelid. These clinical errors can cause ptosis of the upper eyelid, when some of the Botox molecules bind to receptors on the levator oculi muscle, weakening that muscle's ability to lift the upper eyelid. Alternatively, or perhaps concomitantly, if the patient is particularly unlucky, high doses of Botox injected into incorrect locations in the forehead can create, or exacerbate pre-existing minor brow ptosis, forcing the patient to exert greater effort in firing the frontalis muscle to elevate the soft tissue of the brow, so that the patient's superior field of vision is less obscured. This increased activity of the frontalis muscle can also induce headaches in some patients. Fortunately, for these patients, the effects of Botox are always transitory, and eventually always disappear completely, although not necessarily immediately. If your headache has the features of a migraine headache, such as photophobia, nausea, pain and discomfort that can become rather severe, you would be well advised to see your primary care physician or to go directly to the Emergency Room of your local hospital for immediate treatment and relief of your symptoms. Luckily, the headaches that most of the extremely small number of patients who do have such a side effect experience from treatment with Botox, are usually much less severe and more transitory than a full blown migraine headache. For these patients, rest, fluids and a day or two of taking over-the-counter extra-strength tylenol, with, or without, the further addition of an NSAID such as ibuprofen or motrin, is sufficient to allow the patient a quick and complete recovery and a rapid return to her normal daily activities.
