Seasonal allergies seem to hang around longer and longer each year – they can start as early as mid-February and sometimes don't let off until November. So you take allergy pills on a regular basis – but did you know, depending on the allergy medicine you take, those pills that let you breathe during the day can have other side effects and medical interactions? If you're curious (or even worried) about the side effects and interactions with other medications that the active ingredient in your allergy medication can have, then here's what you need to know.


Phenylephrine is the active ingredient in medications like Sudafed or Vicks Nasal Spray and is a decongestant first and foremost. Phenylephrine is easy to get by itself over-the-counter and can also be used to combat hemorrhoids and to get rid of male erections that have lasted too long to be safe for the patient. There aren't really any stunning side effects of phenylephrine, but it can increase your blood pressure, so be careful about taking it too often for too long. Interactions with it include amitriptyline (a common migraine medicine), furazolidone, and hyoscyamine.


The most common active ingredient in allergy medications, diphenhydramine is found in the popular allergy medication Benadryl. Diphenhydramine, along with acting as an antihistamine (preventing your soft tissues from swelling and causing stuffed noses and sore throats) also is used to treat extrapyramidal symptoms, motion sickness, and insomnia. Diphenhydramine's side effects are usually contained to drowsiness (it's both why it can be used as an insomnia medication and why you shouldn't drive after taking it), a slightly faster heartbeat, and dry mouth and throat. You shouldn't take it if you're currently on medications such as acetaminophen, tamoxifen, or potassium chloride.


Last (but not least) is hydroxyzine, which is the active ingredient in medicines like Vistaril and Atarax. Hydroxyzine is used by allergy sufferers as an antihistamine, much like diphenhydramine, though it has other uses as an anti-obsessive and antipsychotic medication in those who suffer from clinical anxiety and as a medication for allergic conditions, like utopic and contact dermatoses. It can also be used as a sedative (tranquilizer), most commonly in dental practices and procedures. The side effects of hydroxyzine include drowsiness, hypertension, dry mouth, and headaches, along with a touch of tinnitus, and interacts with medicines such as moxifloaxcin, buprenorphine, clozapine, and acetaminophen.

As with any medication, you should talk to your doctor before starting phenylephrine, diphenhydramine, or hydroxyzine just in case your doctor suspects you may have an allergy to one of these common allergy medications. If you're suffering from allergies and are considering taking one of these medications for relief, schedule an appointment at your local health clinic.