Is Phentermine Safe?

What if you could use Phentermine to lose weight without having to worry about its safety for your health?

Well, this article will help you learn how to minimize possible unpleasant events.

Further reading will provide you with useful info about the safety of Phentermine, factors that influence its safety profile and steps you can make to improve it for the sake of your health.

Is Phentermine safe for your heart?

This is one of the main concerns, because most of future Phentermine users heard of Phentermine allegedly damaging the heart valve.

In fact…

The damage to heart valves was caused by another active substance, which made part of the combined weight loss drug Fen-Phen.

If you check the info more carefully, you will learn that it was not the Phentermine 37.5 mg.

The name of the dangerous drug is Fenfluramine, and it does not make part of the modern Phentermine-containing medications anymore.

But there’s a catch.

Despite the fact that Phentermine will not damage the heart valve as such, it does provide serious changes in your body functioning.

It’s not about the appetite suppression we’re talking now.

It’s about the changes that your body goes through in the “fight-or-flight” mode that the drug induces.

What happens is:

  • Your blood pressure goes up
  • Your heart rate goes up
  • The load on your heart goes up.

Is it a good thing? To work under severe load for a long time?

I bet you know the answer.


To survive such challenge, you need a healthy heart and adequate blood pressure levels.

This is exactly why you need to go through a thorough check, i.e. having your BP and heart rate measured.

If the results are bad, you will not be prescribed Phentermine.

Bonus tip!

If your doctor refuses to issue a prescription for Phentermine because of your health condition, especially poor functioning of the cardiovascular condition, do NOT try to buy Phentermine online or anywhere else.

Heart patients should avoid this appetite suppressant.

It is DANGEROUS for them!

Discuss with your doctor the possibility of using other weight loss drugs or supplements that help cope with excess weight.

Is Phentermine safe to take while pregnant or breastfeeding?

medication on pregnant or breastfeeding womenNo!

Future and breastfeeding mothers, who ask “is Phentermine a safe and effective drug for me, and what side effects can it cause?”, should be asking “will Phentermine harm my baby?” instead.

  • Because it might harm your baby.

Of course, no one checked this medication on pregnant or breastfeeding women.

It would be cold-blooded, if they did.


They did assess the outcome of pregnancies in women, who were using Phentermine as part of combined medications during the first few months of their pregnancies.

  • Some malformations were noted, like cleft lip.

However, the scientists associated the malformations with the use of the second drug that Phentermine was combined with.

Potential safety issues with phentermine/ topiramate include nephrolithiasis, cardiac risk, and teratogenicity.

Even though Phentermine was not discovered to cause any malformations in fetus, it refers to the Pregnancy category:

  • X in the US
  • B3 in Australia

Bonus tip

Women of childbearing age should use reliable contraception methods and do regular pregnancy tests to avoid any potential risks for the future baby.

What factors influence Phentermine safety?

1. Predisposition toward the development of allergic reactions.

If you have a known allergy to the drugs of the same class as Phentermine, or are prone to allergic reactions, you need to start the anti-obesity course with the lowest possible dose.

In addition, you need to carefully assess your condition and immediately address for medical assistance if you notice any allergy-like reactions.

2. Concomitant diseases.

Certain medical conditions increase the risk of unpleasant body response to treatment with Phentermine.

For example, kidney disorders prevent normal excretion of the drug from your body, which results in the drug accumulation.

This, in turn, may cause overdose and serious side effects.

Another example is suffering from diabetes.

Phentermine can alter the effect of diabetic drugs and you need to have their dose adjusted.

Otherwise, you risk suffering from hypoglycemia.

3. Compliance with the dosing regimen and doctor’s recommendations.

Do NOT underestimate the importance of observing an adequate dosing regimen for Phentermine.

Especially when it comes to the amount of pills that you take daily.


Taking more pills will not increase the rate of your weight loss!

Instead, you increase the risk of overdose and consequent adverse reactions.

Still, if you feel like the effects of Phentermine are too strong for you, you may decide to take it every other day.

This doesn’t increase the risks and helps you alleviate unpleasant symptoms, if any.

4. Medications used while taking Phentermine.

ALWAYS consult a doctor or a pharmacist before you take any other medication with Phentermine.

The list of its drug interactions is quite long, and possible reactions are quite severe.

Not every painkiller goes well with this anorectic, and not every flu pill is safe to take with it.

How long can you safely take Phentermine?

A variety of clinical trials have shown that it is safe to take Phentermine up to 3 months in a row.

If you need to lose more weight after you finish the 3-month course, you need to take a 1-2-month break from the drug.

Bonus tip!

User reviews show that there is a high probability that your body develops tolerance to the drug action, if you take it longer than 12 weeks in a row.

Therefore, it is reasonable to take a break, if you are planning to continue the treatment.