The majority of women can take plan B without a problem

and it can be purchased without a prescription at most pharmacies across Canada. It's kept behind the counter so you'll have to ask the pharmacist for it once you're there. There are few side effects and no evidence of any long-term impact on your health or future fertility.

A few medications, however, can interact with emergency contraceptive pills and make them less effective. And there are some medical conditions that may mean plan B is not right for you. Read on for more information on this.

Some people have moral issues with emergency contraception. If you're uncertain about taking plan B, speak to your doctor first or talk to a professional who shares your background and beliefs.

I think my contraception let me down

It's called plan B for a reason: because it's meant for times when your first method of birth control (your "plan A") has let you down and you're worried you might get pregnant.

Accidents happen -- condoms break, we forget to take our birth control pills, diaphragms slip -- maybe you didn't even intend to have sex. No matter what happened, if you're worried about getting pregnant and you know it's not the right time for you, there's no need to panic. You can use plan B as your emergency backup plan.

But remember, the sooner you act, the more effective plan B will be. Ideally, take it within 24 hours and at most, 72 hours after unprotected sex, or when your contraceptive fails.

What about side effects?

Most women won't experience any dramatic side effects from taking plan B. Typically, you can carry on with your usual activities. If you do have a headache or feel sick, it should pass fairly quickly. If it doesn't, consult your doctor.

plan B is the most advanced form of emergency contraceptive and side effects in general are less likely because it has no estrogen - only progestin. As well as being easier to tolerate than earlier pills, it's also more effective at preventing pregnancy.

Some women will feel side effects after taking plan B, such as breast tenderness, headaches, stomach pains, diarrhea, dizziness or fatigue. These symptoms are usually minor and should get better after a few days. If you're worried, talk to your pharmacist or speak to the doctor or nurse where you were given plan B.

The most common adverse effects reported by women are:

Nausea - in 23% of women
Abdominal pain - in 18% of women
Fatigue - in 17% of women
Headaches - in 17% of women
Vomiting - in 6% of women
Other less common side effects - breast tenderness, dizziness and diarrhea have been reported by some women who have used plan B and may be related to the drug

Call your doctor immediately if you experience the following symptoms and signs of serious adverse effects:

Itching all over your body
Cramping or severe pain in your stomach or belly prior to your next normal period
- Sickness
  After taking plan B, a few women (approximately 6 out of 100) will be sick (vomit). If you get sick within 1 hour of taking the pill, you need to go back to your pharmacist, doctor or health clinic who may give you another packet to take again. If you're sick more than 1 hour after you first took the pill, you don't need to take plan B again. If you do feel sick or nauseous after taking the pill, take it easy and rest. If the feelings persist, contact your doctor or local health clinic (your CLSC in Quebec).
- Changes to your period
  plan B has no long-term effect on your monthly cycle. Most women will get their period when expected, but for some, it can also come earlier or later than usual and be lighter or heavier. You might also have some irregular bleeding or "spotting" until your next period.
- Spotting or irregular bleeding before your next period
  Don't worry, this isn't a sign that anything is wrong. It's just the effect of the progestin hormone on your body.
- More than 5-7 days late
  If there's a delay in the onset of your period by more than one week, the possibility of pregnancy should be considered. If this happens to you and you're worried, go to your doctor or health clinic (your CLSC in Quebec) for a pregnancy test. If the test is positive, get some advice about your options from your doctor.
- Late period and pain
  If your period is overdue, and you have pain, contact your doctor or health clinic (your CLSC in Quebec) as soon as possible.

If you do get pregnant, your doctor might want to check for an ectopic pregnancy. An ectopic pregnancy is one that develops outside of the womb, usually in one of the Fallopian tubes. It is a medical emergency. Although ectopic pregnancy is very rare, it is also very serious. So if you are worried, and experience any of the symptoms below, you should see your doctor.

Those symptoms are:

Sudden or unusual pain in the lower abdomen
An unusually light or late period

Can other medications affect plan B?

There are some medications that may interact with plan B and reduce its effectiveness. You should always tell your pharmacist or doctor if you're taking any other medicine or herbal remedies. However, there are no published drug interaction studies of Levonorgestrel, the active ingredient in plan B.

For more information, download the abbreviated product monograph.

Can i take plan B again?

plan B should be saved for emergencies, but there is no medical reason why you can't use it more than once. Don't be afraid to use plan B when you need to, but remember that it should never replace regular, long-term methods of contraception.

plan B doesn't provide long-term protection against future pregnancy, rather, it only works to prevent this one incident.

If you are sexually active, even only occasionally, the best way to take care of your health is to find out about all available contraceptives and discuss them with your doctor.

If you've already taken plan B once since your last period and you now find yourself pregnant, do not take plan B again. It does not work if you already have a confirmed pregnancy.

Medical conditions

Your pharmacist can only supply you with plan B after asking you a few simple questions. These are designed to check that this type of emergency contraception is right for you.

You should not take plan B if:

You already have a confirmed pregnancy
You have hypersensitivity to the ingredients in the pills
You have undiagnosed, abnormal vaginal bleeding

If you're taking any other medication, have known or suspected cancer of the breast, have active liver disease or tumour, have diabetes, you are currently ill, or you have a long-term medical condition, be sure to tell your pharmacist, doctor or health clinic (your CLSC in Quebec) before taking plan B, and ask them what to do next.

For more information, download the abbreviated product monograph.

Objections to plan B

It may be comforting to know that plan B does not work if you are already pregnant. So if you take the pill, you will not be terminating a pregnancy.

plan B does 1 of 3 things:

It temporarily stops the release of an egg from the ovary;
It prevents fertilization; or
It prevents a fertilized egg from attaching to the uterus.

If for some reason the pill does not work and a woman does become pregnant, there is no evidence that plan B harms the fetus in any way.

Although plan B is not an abortifacient (does not cause abortion) as it will not work if a fertilized egg has already attached to the wall of the uterus, some people have religious or ethical concerns over preventing a pregnancy in this way, and therefore emergency contraception might not be the right option for them.

If you're uncertain about taking plan B, first speak to your doctor or talk to a professional who shares your background and beliefs.

Are there any other alternatives?

If you've had unprotected sex, or your contraceptive has failed, and are worried about getting pregnant, you can sometimes have an IUD (intrauterine device) fitted as an alternative to "the morning-after pill." It can be fitted up to 120 hours (5 days) after unprotected sex.

The IUD is a small T-shaped frame with a thin copper coil around the stem, which is inserted into the neck of the womb and must be fitted by a trained health care professional. It is normally used as a method of long-term birth control but can also be used to prevent pregnancy in an emergency.

If you're worried about an unplanned pregnancy, and it's more than 72 hours since you had unprotected sex, or your contraceptive failed, see your doctor or health clinic (your CLSC in Quebec) as soon as possible.